Totally second this. They screwed up by removing all controls.
With the old PiP layout you could go to the previous or next song in a YouTube playlist, you also had the title of the video in there, you could also control the volume from the PiP window. they just screwed it all up with the new layout without controls, why would I use Opera then?
I get the same in Firefox with the addition that in FF you can enable the volume toggle to mute the video.