Earlier today there was a massive spam attack. One very disturbing thing that I noticed was people upvoting spam. This isn't actually only happening here, I've seen it a bit on other sites too. So, this is a reminder. PLEASE DO NOT UPVOTE SPAM! Thank you, and have a nice (hopefully spam free now) day.
I suspect the majority of spam upvotes come from accounts involved in the spamming operations. You'd just need a few initial upvotes, whether accidental or from non-spam posting (possibly aided by chatGPT) to bootstrap to a point where you can upvote a couple of spam accounts to a point where they can start upvoting other spam accounts. If those accounts do not get removed quickly it can just snowball from there.