As I understand it, a new update came out, and that's what problem I immediately found. A new feature has appeared, when you change the tab from video to another, the picture-in-picture mode turns on, and this is very cool. But when you pause the video in PiP or on the tab itself, then PiP remains and does not go anywhere. Also if you close PiP with the button on it, PiP will no longer open until the tab is restarted. Check video (Sorry for the noise) https://youtu.be/OVIIsHMNHl0
Idk, i think its bug. Anyway, browser is very cool, thanks to the developers)