ios 14 update bug

i have just update to ios 14 on my iphone xs and i have a problem: every non-apple app (youtube, instagram, whatsapp etc.) is in a 16:9 aspect ratio, so every time i open them i have these huge black bars on the top and bottom of the screen. has anyone experienced this issue? what can i do? i have already tried to restart the phone, but to no avail. thank you