Alabalcho :
Create new Chrome profile. Google has placed a cookie that "Russian ads are OK", this cookie might have come from many places, not necessary from malware.
This isn't a cookie. It isn't the native ads on the site. I have this exact malware and it IS some type of malware. The dead giveaway is that it triggers ads even when subscribed to YouTube Red, as I am, and in fact inserts them into and overtop of YouTube content. It only appears to affect YouTube specifically and only in Google Chrome, as the other browsers on my computer do not share this problem. It also produces non-explicit but very obvious porn and dating site advertisements, and you can bet your boots Google isn't putting those on YouTube.
Scans with both Windows Defender and Malwarebytes do not detect the source of the malware, however Malwarebytes Premium frequently detects the sites used by this adware as being malicious. Another frequent symptom of this is that sometimes simply clicking anywhere on your browser window (regardless of it being YouTube or not) will trigger a pop-up ad in spite of adblockers, but these are the most frequent things that Malwarebytes Premium catches and blocks.
Since a fresh install seems to be the only way to go here, I'm going to do that. But I wanted to register that this is indeed some type of malware problem and not some funky tomfoolery with locations or cookies that affect Google's own ad service.