Text messages reappear immediately after deleting

Immediately after I swipe left on a (very small) thread of text messages, and click the red delete button, it disappears for about three seconds before immediately reappearing. It only occurs for this specific person, no one else. I have tried changing the Keep Messages time period, blocking their number, pinning, unpinning, deleting. I am fully updated to iOS 16.0.2. Nothing will delete these messages. It is not necessarily important that they get deleted, it is just an annoyance.

Edit: If I search for a word in said text message thread, it does not show up, implying that they are deleted. But, nonetheless, I can still physically see them.