It was grok 3, and it was tricked/prompted to reply like so, just like any other LLM can be. Apparently at one point it was prompted with a choice between identifying itself as a MechaHitler or a GigaJew, so it chose the former.
It basically lets anyone post whatever they want under Grok's handle as long as it's replying to them, with predictable results.
The giveaway is that all the screenshots floating around show grok giving replies to single-purpose troll accounts
I'm not sure I understand what you mean by that. What else would it reply as?
Questionable.