Given they all lacked necessary details, these downvotes were legitimate, but were grabbed by the serial vote detector because it very obviously looks like targeted voting to a robot.
Let me clarify: this has nothing to do with robots. Those votes were grabbed by the serial vote detector because they were in fact serial votes. You voted a ton on the same person's posts in a small window of time, and the system considers that to be serial voting and to be inherently illegitimate. This has nothing to do with robots and everything to do with making sure one person does not unjustly target another person and mess with our systems. You didn't act with malicious intent, and each of those votes was individually legitimate, but the serial voting script doesn't know this and places no value judgement on vote legitimacy—it just looks at whether the votes are serial.
Can this be undone? I know I can go and downvote them again, but that will just get reversed again as it will appear once again as serial voting.
Moderators can't reverse the serial voting script's actions. Those votes are simply undone and gone.
Just ... don't re-do all these downvotes again. It'll just be caught and rolled back as serial voting again, and nobody can prevent that. I don't suggest trying to find a way to do it anyway since circumventing our anti-abuse mechanisms is generally a bad idea and done at your peril. There are other people beside you who will also be voting and helping to take care of things.
I know those questions all share the same flaws, but they're all closed now. Downvotes on a couple of those posts is plenty. Some of those might still warrant downvotes on an individual basis, but you can't do that without it counting as serial voting again. The situation is being handled though and things will be fine even without them being downvoted. Now's the time to let The Process™ do its work, and focus on next steps for taking care of things: we're engaging already with the author to provide feedback and get more detail.
This does raise rate limiting questions, such that maybe even a 2k user shouldn't be able to ask eight questions in the span of twelve minutes, so that the community has time to deal with problems that might show up in the first two or three and would otherwise show up in the rest, but that's a separate topic to the voting.