diff --git a/common/src/main/java/com/viaversion/viabackwards/api/rewriters/BackwardsStructuredItemRewriter.java b/common/src/main/java/com/viaversion/viabackwards/api/rewriters/BackwardsStructuredItemRewriter.java
index bbb3479e..c799b270 100644
--- a/common/src/main/java/com/viaversion/viabackwards/api/rewriters/BackwardsStructuredItemRewriter.java
+++ b/common/src/main/java/com/viaversion/viabackwards/api/rewriters/BackwardsStructuredItemRewriter.java
@@ -32,8 +32,10 @@ import com.viaversion.viaversion.api.minecraft.HolderSet;
 import com.viaversion.viaversion.api.minecraft.data.StructuredDataContainer;
 import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
 import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.minecraft.item.data.CustomModelData1_21_4;
 import com.viaversion.viaversion.api.protocol.packet.ClientboundPacketType;
 import com.viaversion.viaversion.api.protocol.packet.ServerboundPacketType;
+import com.viaversion.viaversion.api.protocol.version.ProtocolVersion;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.rewriter.StructuredItemRewriter;
 import java.util.ArrayList;
@@ -88,8 +90,19 @@ public class BackwardsStructuredItemRewriter<C extends ClientboundPacketType, S
         item.setIdentifier(mappedItem.id());
 
         // Add custom model data
-        if (mappedItem.customModelData() != null && !dataContainer.has(StructuredDataKey.CUSTOM_MODEL_DATA)) {
-            dataContainer.set(StructuredDataKey.CUSTOM_MODEL_DATA, mappedItem.customModelData());
+        if (mappedItem.customModelData() != null) {
+            if (connection.getProtocolInfo().protocolVersion().newerThanOrEqualTo(ProtocolVersion.v1_21_4)) {
+                if (!dataContainer.has(StructuredDataKey.CUSTOM_MODEL_DATA1_21_4)) {
+                    dataContainer.set(StructuredDataKey.CUSTOM_MODEL_DATA1_21_4, new CustomModelData1_21_4(
+                        new float[]{mappedItem.customModelData().floatValue()},
+                        new boolean[0],
+                        new String[0],
+                        new int[0]
+                    ));
+                }
+            } else if (!dataContainer.has(StructuredDataKey.CUSTOM_MODEL_DATA1_20_5)) {
+                dataContainer.set(StructuredDataKey.CUSTOM_MODEL_DATA1_20_5, mappedItem.customModelData());
+            }
         }
 
         // Set custom name - only done if there is no original one
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/Protocol1_21_4To1_21_2.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/Protocol1_21_4To1_21_2.java
index cba8eeba..3ae59ecd 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/Protocol1_21_4To1_21_2.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/Protocol1_21_4To1_21_2.java
@@ -23,7 +23,7 @@ import com.viaversion.viabackwards.api.rewriters.SoundRewriter;
 import com.viaversion.viabackwards.api.rewriters.TranslatableRewriter;
 import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter.BlockItemPacketRewriter1_21_4;
 import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter.ComponentRewriter1_21_4;
-import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter.EntityPacketRewriter1_99;
+import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter.EntityPacketRewriter1_21_4;
 import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter.ParticleRewriter1_21_4;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Particle;
@@ -54,7 +54,7 @@ import static com.viaversion.viaversion.util.ProtocolUtil.packetTypeMap;
 public final class Protocol1_21_4To1_21_2 extends BackwardsProtocol<ClientboundPacket1_21_2, ClientboundPacket1_21_2, ServerboundPacket1_21_4, ServerboundPacket1_21_2> {
 
     public static final BackwardsMappingData MAPPINGS = new BackwardsMappingData("1.21.4", "1.21.2", Protocol1_21_2To1_21_4.class);
-    private final EntityPacketRewriter1_99 entityRewriter = new EntityPacketRewriter1_99(this);
+    private final EntityPacketRewriter1_21_4 entityRewriter = new EntityPacketRewriter1_21_4(this);
     private final BlockItemPacketRewriter1_21_4 itemRewriter = new BlockItemPacketRewriter1_21_4(this);
     private final ParticleRewriter<ClientboundPacket1_21_2> particleRewriter = new ParticleRewriter1_21_4(this);
     private final TranslatableRewriter<ClientboundPacket1_21_2> translatableRewriter = new ComponentRewriter1_21_4(this);
@@ -148,7 +148,6 @@ public final class Protocol1_21_4To1_21_2 extends BackwardsProtocol<ClientboundP
                     translatableRewriter.processTag(wrapper.user(), wrapper.passthrough(Types.OPTIONAL_TAG));
                 }
                 if (actions.get(6)) {
-                    actions.clear(6);
                     wrapper.passthrough(Types.VAR_INT); // List order
                 }
 
@@ -171,7 +170,7 @@ public final class Protocol1_21_4To1_21_2 extends BackwardsProtocol<ClientboundP
     }
 
     @Override
-    public EntityPacketRewriter1_99 getEntityRewriter() {
+    public EntityPacketRewriter1_21_4 getEntityRewriter() {
         return entityRewriter;
     }
 
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/BlockItemPacketRewriter1_21_4.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/BlockItemPacketRewriter1_21_4.java
index 599e5c63..d6fe8238 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/BlockItemPacketRewriter1_21_4.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/BlockItemPacketRewriter1_21_4.java
@@ -17,8 +17,18 @@
  */
 package com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.rewriter;
 
+import com.viaversion.nbt.tag.ByteArrayTag;
+import com.viaversion.nbt.tag.CompoundTag;
+import com.viaversion.nbt.tag.IntArrayTag;
+import com.viaversion.nbt.tag.ListTag;
+import com.viaversion.nbt.tag.StringTag;
 import com.viaversion.viabackwards.api.rewriters.BackwardsStructuredItemRewriter;
 import com.viaversion.viabackwards.protocol.v1_21_4to1_21_2.Protocol1_21_4To1_21_2;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataContainer;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.minecraft.item.data.CustomModelData1_21_4;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.chunk.ChunkType1_20_2;
 import com.viaversion.viaversion.api.type.types.version.Types1_21_2;
@@ -30,6 +40,9 @@ import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ServerboundPacke
 import com.viaversion.viaversion.rewriter.BlockRewriter;
 import com.viaversion.viaversion.rewriter.RecipeDisplayRewriter;
 
+import static com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter.BlockItemPacketRewriter1_21_4.downgradeItemData;
+import static com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter.BlockItemPacketRewriter1_21_4.updateItemData;
+
 public final class BlockItemPacketRewriter1_21_4 extends BackwardsStructuredItemRewriter<ClientboundPacket1_21_2, ServerboundPacket1_21_2, Protocol1_21_4To1_21_2> {
 
     public BlockItemPacketRewriter1_21_4(final Protocol1_21_4To1_21_2 protocol) {
@@ -72,4 +85,83 @@ public final class BlockItemPacketRewriter1_21_4 extends BackwardsStructuredItem
         recipeRewriter.registerRecipeBookAdd(ClientboundPackets1_21_2.RECIPE_BOOK_ADD);
         recipeRewriter.registerPlaceGhostRecipe(ClientboundPackets1_21_2.PLACE_GHOST_RECIPE);
     }
+
+
+    @Override
+    public Item handleItemToClient(final UserConnection connection, final Item item) {
+        super.handleItemToClient(connection, item);
+
+        final StructuredDataContainer dataContainer = item.dataContainer();
+        final CustomModelData1_21_4 modelData = dataContainer.get(StructuredDataKey.CUSTOM_MODEL_DATA1_21_4);
+        if (modelData != null) {
+            saveTag(createCustomTag(item), customModelDataToTag(modelData), "custom_model_data");
+        }
+
+        updateItemData(item);
+        return item;
+    }
+
+    @Override
+    public Item handleItemToServer(final UserConnection connection, final Item item) {
+        super.handleItemToServer(connection, item);
+
+        final StructuredDataContainer dataContainer = item.dataContainer();
+        final CompoundTag customData = dataContainer.get(StructuredDataKey.CUSTOM_DATA);
+        if (customData != null) {
+            if (customData.remove(nbtTagName("custom_model_data")) instanceof final CompoundTag customModelData) {
+                dataContainer.set(StructuredDataKey.CUSTOM_MODEL_DATA1_21_4, customModelDataFromTag(customModelData));
+                removeCustomTag(dataContainer, customData);
+            }
+        }
+
+        downgradeItemData(item);
+        return item;
+    }
+
+    private CustomModelData1_21_4 customModelDataFromTag(final CompoundTag tag) {
+        final IntArrayTag floatsTag = tag.getIntArrayTag("floats");
+        final float[] floats = new float[floatsTag.getValue().length];
+        for (int i = 0; i < floats.length; i++) {
+            floats[i] = Float.intBitsToFloat(floatsTag.get(i));
+        }
+
+        final ByteArrayTag booleansTag = tag.getByteArrayTag("booleans");
+        final boolean[] booleans = new boolean[booleansTag.getValue().length];
+        for (int i = 0; i < booleans.length; i++) {
+            booleans[i] = booleansTag.get(i) != 0;
+        }
+
+        final ListTag<StringTag> stringsTag = tag.getListTag("strings", StringTag.class);
+        final String[] strings = new String[stringsTag.size()];
+        for (int i = 0; i < strings.length; i++) {
+            strings[i] = stringsTag.get(i).getValue();
+        }
+
+        final IntArrayTag colorsTag = tag.getIntArrayTag("colors");
+        return new CustomModelData1_21_4(floats, booleans, strings, colorsTag.getValue());
+    }
+
+    private CompoundTag customModelDataToTag(final CustomModelData1_21_4 customModelData) {
+        final CompoundTag tag = new CompoundTag();
+        final int[] floats = new int[customModelData.floats().length];
+        for (int i = 0; i < floats.length; i++) {
+            floats[i] = Float.floatToIntBits(customModelData.floats()[i]);
+        }
+        tag.put("floats", new IntArrayTag(floats));
+
+        final byte[] booleans = new byte[customModelData.booleans().length];
+        for (int i = 0; i < booleans.length; i++) {
+            booleans[i] = (byte) (customModelData.booleans()[i] ? 1 : 0);
+        }
+        tag.put("booleans", new ByteArrayTag(booleans));
+
+        final ListTag<StringTag> strings = new ListTag<>(StringTag.class);
+        for (final String string : customModelData.strings()) {
+            strings.add(new StringTag(string));
+        }
+        tag.put("strings", strings);
+
+        tag.put("colors", new IntArrayTag(customModelData.colors()));
+        return tag;
+    }
 }
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/ComponentRewriter1_21_4.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/ComponentRewriter1_21_4.java
index 7df3333b..2b4f6523 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/ComponentRewriter1_21_4.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/ComponentRewriter1_21_4.java
@@ -23,6 +23,7 @@ import com.viaversion.viabackwards.api.rewriters.TranslatableRewriter;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ClientboundPacket1_21_2;
 import com.viaversion.viaversion.util.SerializerVersion;
+import com.viaversion.viaversion.util.TagUtil;
 
 public final class ComponentRewriter1_21_4 extends TranslatableRewriter<ClientboundPacket1_21_2> {
 
@@ -37,8 +38,7 @@ public final class ComponentRewriter1_21_4 extends TranslatableRewriter<Clientbo
             return;
         }
 
-        // Remove or update data from componentsTag
-        // New added data which is not handled otherwise needs to be removed to prevent errors on the client
+        TagUtil.removeNamespaced(componentsTag, "custom_model_data");
     }
 
     @Override
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_99.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_21_4.java
similarity index 73%
rename from common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_99.java
rename to common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_21_4.java
index 1a06694a..592cb767 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_99.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21_4to1_21_2/rewriter/EntityPacketRewriter1_21_4.java
@@ -25,18 +25,21 @@ import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.RegistryEntry;
 import com.viaversion.viaversion.api.minecraft.entities.EntityType;
 import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_21_2;
+import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.version.Types1_21_2;
 import com.viaversion.viaversion.api.type.types.version.Types1_21_4;
 import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundConfigurationPackets1_21;
+import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.packet.ServerboundPackets1_21_4;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ClientboundPacket1_21_2;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ClientboundPackets1_21_2;
+import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ServerboundPackets1_21_2;
 import com.viaversion.viaversion.rewriter.RegistryDataRewriter;
 import com.viaversion.viaversion.util.Key;
 
-public final class EntityPacketRewriter1_99 extends EntityRewriter<ClientboundPacket1_21_2, Protocol1_21_4To1_21_2> {
+public final class EntityPacketRewriter1_21_4 extends EntityRewriter<ClientboundPacket1_21_2, Protocol1_21_4To1_21_2> {
 
-    public EntityPacketRewriter1_99(final Protocol1_21_4To1_21_2 protocol) {
+    public EntityPacketRewriter1_21_4(final Protocol1_21_4To1_21_2 protocol) {
         super(protocol, Types1_21_4.ENTITY_DATA_TYPES.optionalComponentType, Types1_21_4.ENTITY_DATA_TYPES.booleanType);
     }
 
@@ -49,7 +52,8 @@ public final class EntityPacketRewriter1_99 extends EntityRewriter<ClientboundPa
         final RegistryDataRewriter registryDataRewriter = new RegistryDataRewriter(protocol) {
             @Override
             public RegistryEntry[] handle(final UserConnection connection, final String key, final RegistryEntry[] entries) {
-                if (Key.stripMinecraftNamespace(key).equals("worldgen/biome")) {
+                final String strippedKey = Key.stripMinecraftNamespace(key);
+                if (strippedKey.equals("worldgen/biome")) {
                     for (final RegistryEntry entry : entries) {
                         if (entry.tag() == null) {
                             continue;
@@ -70,6 +74,15 @@ public final class EntityPacketRewriter1_99 extends EntityRewriter<ClientboundPa
                         final CompoundTag musicTag = weightedMusicTags.get(0);
                         effectsTag.put("music", musicTag.get("data"));
                     }
+                } else if (strippedKey.equals("trim_material")) {
+                    for (final RegistryEntry entry : entries) {
+                        if (entry.tag() == null) {
+                            continue;
+                        }
+
+                        final CompoundTag compoundTag = ((CompoundTag) entry.tag());
+                        compoundTag.putFloat("item_model_index", itemModelIndex(entry.key()));
+                    }
                 }
 
                 return super.handle(connection, key, entries);
@@ -92,13 +105,44 @@ public final class EntityPacketRewriter1_99 extends EntityRewriter<ClientboundPa
             final String world = wrapper.passthrough(Types.STRING);
             trackWorldDataByKey1_20_5(wrapper.user(), dimensionId, world);
             trackPlayer(wrapper.user(), entityId);
+
+            final PacketWrapper playerLoadedPacket = wrapper.create(ServerboundPackets1_21_4.PLAYER_LOADED);
+            playerLoadedPacket.scheduleSendToServer(Protocol1_21_4To1_21_2.class);
         });
 
         protocol.registerClientbound(ClientboundPackets1_21_2.RESPAWN, wrapper -> {
             final int dimensionId = wrapper.passthrough(Types.VAR_INT);
             final String world = wrapper.passthrough(Types.STRING);
             trackWorldDataByKey1_20_5(wrapper.user(), dimensionId, world);
+
+            final PacketWrapper playerLoadedPacket = wrapper.create(ServerboundPackets1_21_4.PLAYER_LOADED);
+            playerLoadedPacket.scheduleSendToServer(Protocol1_21_4To1_21_2.class);
         });
+
+        protocol.registerServerbound(ServerboundPackets1_21_2.MOVE_VEHICLE, wrapper -> {
+            wrapper.passthrough(Types.DOUBLE); // X
+            wrapper.passthrough(Types.DOUBLE); // Y
+            wrapper.passthrough(Types.DOUBLE); // Z
+            wrapper.passthrough(Types.FLOAT); // Yaw
+            wrapper.passthrough(Types.FLOAT); // Pitch
+            wrapper.write(Types.BOOLEAN, true); // On ground // TODO ...
+        });
+    }
+
+    private float itemModelIndex(final String trim) {
+        return switch (Key.stripNamespace(trim)) {
+            case "amethyst" -> 1.0F;
+            case "copper" -> 0.5F;
+            case "diamond" -> 0.8F;
+            case "emerald" -> 0.7F;
+            case "gold" -> 0.6F;
+            case "iron" -> 0.2F;
+            case "lapis" -> 0.9F;
+            case "netherite" -> 0.3F;
+            case "quartz" -> 0.1F;
+            case "redstone" -> 0.4F;
+            default -> 1.0f;
+        };
     }
 
     @Override