The default keyboard shortcut used to open the Activity Switcher has been changed to Meta+A, so that its prior shortcut Meta+Tab can be used some something else, which is coming soon…

a new overview or desktop grid like window management feature perhaps? They've been really on point lately so I'm excited to see what they have in mind.

It feels a bit too much like YouTube and the removal of the dislike button to me.

That was a crucially different situation. On Youtube, users didn't control communities or make the rules, so disliking, even though it had many issues, was the only way to discourage bad content. Things are different here. Individual users have much more control so downvotes aren't needed like they were on Youtube. You don't lose much except the downsides.

Downvotes seem to only spread negativity and discourage contribution. as others have said, you can just report posts if they're breaking the rules, so I don't really get the point of downvotes anyway. Better posts will rise above it even when downvotes are disabled.