safari full screen video bug

since a week suddenly videos stopped being full screen...when i tap on full screen button the size of the video is same as in preview ,i only get black borders all around the video.i installed chrome and firefox and both work good.Tried youtube videos on safari and seem to be the only ones which have no problem . every video i try to view in full screen ,streaming,news etc are all bugged on safari...i just updated the ipad pro 11 to ios 12.4 and have same issue,no new apps installed nor changed any settings..tried pinching ,zooming but nothing to do..how can i fix this?

here’s an example of how it looks like

https://drive.google.com/file/d/1bSD_Y0-thzYfSu6wFQyj-ey043-SQ2Cj/view?usp=drivesdk