Two big things I’ve noticed:

1. They removed the Chromecast queue feature. So if I’m casting to my TV, I can either play one video at a time, or I can enable autoplay and see what the algorithm decides to serve me - I can’t queue up a few videos and just watch those, like I used to be able to.

2. Playlists are becoming harder and harder to use. Finding the button to add a video to a playlist, moving videos from one playlist to another, and managing playlists in general has all become more difficult recently.