Paper/paper-server/nms-patches/net/minecraft/world/entity/monster/EntityGuardianElder.patch

--- a/net/minecraft/world/entity/monster/EntityGuardianElder.java
+++ b/net/minecraft/world/entity/monster/EntityGuardianElder.java
@@ -79,7 +79,7 @@
 
                 if (!entityplayer.hasEffect(mobeffectlist) || entityplayer.getEffect(mobeffectlist).getAmplifier() < 2 || entityplayer.getEffect(mobeffectlist).getDuration() < 1200) {
                     entityplayer.connection.send(new PacketPlayOutGameStateChange(PacketPlayOutGameStateChange.GUARDIAN_ELDER_EFFECT, this.isSilent() ? 0.0F : 1.0F));
-                    entityplayer.addEffect(new MobEffect(mobeffectlist, 6000, 2), this);
+                    entityplayer.addEffect(new MobEffect(mobeffectlist, 6000, 2), this, org.bukkit.event.entity.EntityPotionEffectEvent.Cause.ATTACK); // CraftBukkit
                 }
             }
         }