According to the GitHub issue, YouTube didn’t change anything. There are two endpoints that can be used to attribute a view. One is called multiple times throughout a video playback and has been in the easylist privacy filter for years. The other is called at the start of a playback, and was just added to the list (the timing lines up with the reports of view drops from tech YouTubers).

This is not definitive proof that easylist caused the view drops, but it’s I’ve read the issue and a writeup by a YouTube creator and it seems pretty likely.