I'm curious! Can cavities reappear even in treated teeth?

I have a tooth that had a cavity treated a while ago, and I thought it would be fine now that it was treated.

However, I’ve heard from people around me that even treated teeth can develop cavities again if not properly cared for, so I’m suddenly worried.

Has anyone actually gotten a cavity again in a spot they just treated? I'm curious about the circumstances under which it recurs and how you manage it! Please share your experience :) ^^;