This has been happening for years. My theory is the actors running the bots are instructing their bots to use old popular threads as a blueprint to get a bunch of upvotes across all of their accounts at once. The idea being that clearly Reddit users liked the original posts and comments in the past, so the users will upvote it again. Then they sell the accounts to bad actors who are interested in purchasing accounts with real looking post histories.
They don't sell their account to bad actors much anymore, instead they sell services. Want this product or that news story or this ... To have lots of comments and upvote from tens of account. If you search a little you can easily find those shops, they sell for every social media out there and you pay per "thousands of likes" or stuff like that.
They used to be based on super low paid human, then it was bot train the account up then humans use it when it's cooked, and I guess we're now entering the bot from top to bottom era.
If I were Reddit I'd be running some sort of counter-offensive, throwing a few hundred dollars at those services and flagging accounts which upvote my poison pill as sockpuppets.
Yup this is a very old strategy. Years back when I was helping mod a very large (10/15m+) sub, the head mod was running a pipeline in the background to help detect this exact thing.
