I've used LLMs quite a lot (Claude, GPT) and have never seen this behavior. You've got something else going on.

I've used LLMs all day five days a week plus my own free time for the last year or so (new job).

I've seen plenty of hallucinations and context collapse behaviours.

I've never seen that.

Worth looking at https://www.anthropic.com/engineering/a-postmortem-of-three-...

They can “go insane” but it seems often to be infra related as opposed to anything one would consider hallucination. Smaller models will often get stuck repeating a word or phrase forever but that’s a bit different and nobody would call it hallucination.

One annoying one is we have an LLM-as-a-judge that is supposed to quote parts of a transcript to justify its reasoning, and sometimes it’ll get stuck on something short like “No.” and then just endlessly repeat it: “4. No. 5. No. […] 728. No. […] 1435. No. …”