They gave "official" sources preferential treatment in the SERPs. Now you are bombarded with shitty TV news anchor videos. There are also government videos pushed to the top like from the CDC. People (or bots, who knows) dislike these videos. And they end up with a overwhelming dislikes. I don't think Google wants other people to be influenced by the majority dislikes. They want their authority news sources to be respected.

I actually support the removal of the dislikes. Before, YouTube would just change the dislike count. You could go to a video and come back later and the dislike count would be lower. (Maybe they are banning bots? Or maybe just manipulating the result. Or maybe just eventually consistent haha)