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)
Steam review scores are more robust than what 20 games critics thought about a game and is more resistant to review bombing than metacritic. The score is not meaningless IMO.