Hmm...Im not having this problem at all (iPhone 11, 13.1.2).
I just loaded a video in youtube, switched to instagram and browsed, switched to reddit and browsed, switched to news, switched to photos, switched to safari, and back to youtube. Video was still in the same spot as i left it, and all my other apps were where i left them as well.
I just loaded a video in youtube, switched to instagram and browsed, switched to reddit and browsed, switched to news, switched to photos, switched to safari, and back to youtube. Video was still in the same spot as i left it, and all my other apps were where i left them as well.