Online gambling, most of which is about good ol’ money laundering, and thepiratebay seems to not censor their ads at all, so you may get all kinds of scams and malware spread via ads.
I dunno, but torrenting sites gladly use networks that use malicious redirects, especially on mobile. I also saw ads specifically for gambling companies that were known bad actors, at least to me, given what people were behind them. Won't give you examples, it was years ago. It was like that, you go to a site to get your Linux ISOs, and it's plastered in certain company's ads. Wham, in a month you get investigative articles about that very company's owners and who they are tied to.
It's also of note that on Facebook I don't get many online casino ads, I get mostly reMarkable ads, there was one from Roli when they launched their new instrument, and others were mostly advertising stuff to me that I already bought elsewhere. I think it might be because I had banned the first dozen of such ads, and they stopped coming.
Same. Also I probably get more Russia-sponsored content from Meta than I can see on Rutracker. The internet, lead by big tech, has long passed the point where a banner advertising online gambling could be seen as something outrageous