Youtube Fullscreen persists and breaks on app switch

(On android samsung, using mobile browser) When I use fullscreen mode on the mobile Youtube website, the fullscreen breaks the screen rotation mode when i leave the firefox app and bring it back into focus. It will force (if possible) all tabs currently open into horizontal mode, and I have to navigate back to that youtube page, click the fullscreen button, exit fullscreen, then navigate to other tabs to fix it... temporarily. If I leave firefox again and navigate to the same tab that had the bugged video, it will start to force horizontal orientation again. It does not do this all the time, but it does this often enough while I am watching videos.