I know I’m late to the party but I just found out and didn’t find a post regarding this
TL;DR: Steam now calculates review scores based on reviews made on your languages only (if enough). This is on by default, but can be reverted to go back to review scores based on all reviews (from people that purchased the game directly on Steam only)
I mean yeah and that‘s very unfortunate. Users need more control over these things. This is as rushed as Youtube‘s automatic translation slop. Most people speak more than one language. When will Americans learn that?