Yes! Deepseek does this to me all the time.

I had 20 something files I wanted it to check and change something. The first 5 or so it did, then the sixth it rightly said everything is correct moving on. It said that for the rest of the 20, the same text over and over.

I checked, and file 6 was the only correct one. It like, learned to just repeat itself after that and did nothing.