Patterns on the [https://wordpress.org/patterns/ Pattern Directory] can have keywords for better discoverability while searching. The way these are stored [69548ff1f0 was changed from a taxonomy to meta value], but the `/wp/v2/pattern-directory/patterns` endpoint was still pulling from that old value.
The correct property to use for this field is `meta.wpop_keywords`, which returns a single string with comma-separated keywords.
Props ryelle, TimothyBlynJacobs.
See #56126.
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