Likes from logged in views do count, the like to view ratio is higher due to that.
A German YouTuber tested it with an unlisted video, I can’t find it as of now but I do find a lot of deleted videos in my liked ones…
Basic theory as of the time of the video is that they want to go against bot views. Short views did not decline, only long form video, and of those the people with mostly desktop views are hit the most.
Edit: found it!
So far I’ve seen RedLetterMedia blame Restricted mode. Then saw SpiffingBrit refute that. Some comments I saw blamed ad blockers.
Then I checked out, not my problem. It’s a black box everyone is trying to solve.
Restricted mode is only turned on if that account does only watch restricted videos.