Keywords declined as not meeting contribution guidelines despite being existing keywords.

Recently, I've started having keywords declined despite them already existing in the system.

In contribution 210325-003841-806000, keyword reference-to-amazon.com was declined despite already being attached to 134 titles. I have this keyword declined, a lot, and I have no idea why. Any explanation would be appreciated.

In contribution 210323-015418-427000, keyword n-word was declined despite being attached to 452 titles. I've never had this one declined before.