Thats torture, for once i thought they should be there.
I can only see it as camera place, which is why they put a black bar onto it.
And, for player that want to remove that, go to phone setting>display>camera cutout (or Full screen apps on oneui4.1)
From there, select the game you dont want to see black bar on camera side. And set to “Show camera cutout”.
Now you might find annoying when theres a camera hole on it, but if you dont care much about it, thats fine.