Today I created a copy of a card and edited the new card, including changing the card title. The new and old card still shared the same word ("working") in their titles. When I searched for the new card with the term "working," it did not come up in the results, though the old card still did. I refreshed the page and retried, no dice. The new card did not come up in the results until I shut Trello down completely and reopened it. I then repeated this with another pair of cards. Same results, except I had to shut Trello down twice before the problem resolved.
I researched the community and found the thread addressing the same problem from 2019. However, it doesn't help me because the solution was that it was a system problem that was repaired. If that's what it is now, I'm trying to get the problem on Support's radar since the support request page just points you to guides or this community. Confirmation that others are having the same/similar issue would be welcome.