I lived in a country where people don't speak English. There's a sizable expat community of English speaking workers there. The ad targeting was so useless that I was constantly shown ads in a language I couldn't understand. This was on an Android phone where everything was set to English. With every single interaction I with any app or web page I was broadcasting the language I know, and yet they couldn't figure even that absolutely critical detail out.
This targeting was so bad that an old fashioned newspaper ad printed in ink next to a story would have been more effective. At least a publisher is going to put English ads in an English newspaper, German ads in a German newspaper, etc.
If the ad companies can't even figure out the language(s) that their targets understand, their knowledge of their target must be essentially zero.