That's been going on for quite some time. Back before the migration i can see some user intentionally combing reddit to find out who is botting and calling them out. Of course, no action taken.
It's way worse now though. I don't know if the bots ramped up or if there's just more exposure since there's fewer users but it is so much more obvious now. But yeah, OP should not be surprised to see repost bots. What's worse is how many comments are now bots too, and not just repost bots of popular comments, buts actual LLM responses.
Damn, it's just sad. I guess the smaller sub still better? It's always the big time waster sub that have this issue back then, while the smaller sub tend to be more organic.
Bot accounts farming karma, since karma actually became a useful currency on Reddit once communities started restricting accounts from posting or commenting that didn't have scores over a certain threshold. Then those bot accounts with "real" looking karma scores can go spew out commercial and political advertisements anywhere else.
SDV and other niche subs get hit because even without the bots there all upvoting each other, it was already a happy go lucky upvote party.
Has been an issue for a while. The sub of ~30k I was a mod in, I was picked up because I was reporting bot posts and posting the OG posts. I was modded by one the other mod (the sub owner was non-existent really) so instead of me being the middle man, I would just respond with the OG post so there was a "trail" and then remove the post.
I did other little things like discussion threads for the weekly event, but I just hated seeing the bots. It died down after a few months, so they have to be watching the metrics on the subs to know where it's allowed and where it isn't.