One thing I've thought of trying is, if I ever get around to putting things back online, loading the pages with altered versions of themselves in a manner that human users are unlikely to see (though they could if they wanted to) but scrapers are unlikely to ignore (because they look enough like something users might see, perhaps by opening a <detail> tag).
The altered versions would be the page or paragraphs of it, with sentences and words swapped arbitrarily so that training on the data adds as many iffy token sequences as correct ones.
To be clear, making pages with bad training data for bots won't make the bots go away.
It'll just punish the bad actors running the scrapers. As the original poster mentions that they are using TVs as proxies to get residential IPs, one really can't think of these bots as criminal enterprises.
Sadly, if the bad actors has two cents for brain, they'll limit how much importance each domain name can have on training data. To mitigate impact of bad data like this.
(Note I'd suggest only linking to them from robot.txt as pages to not be indexed, that way no human or well behaved not ever will see them, which is kind of the point).