I started having a similar issue with Spotify a couple years ago. Eventually I discovered that someone else was using my (free) account to listen to bunch of Spanish-language music that I'd never heard of. I don't think my Spotify recommendations ever recovered.

> recently YouTube has been serving me exclusively Spanish-language ads

This has been happening to me, but on Twitter! I know a very basic amount of Spanish, but am a non-hispanic dude in semi-rural Texas.

> semi-rural Texas

Pattern matched.

LOL, w-a-y b-a-c-k when it was only your name and address that was sold to marketers and the spam was snail mail, friends and I would sing up for things, order catalogs etc. using a different name each time. Then when the junk mail came you knew who sold you out.

Looks like this data has been collected through the official API, so you could just query yourself in there.

I'm too lazy, that's why I appreciate these hackers who go to all the trouble on my behalf for free!