Why is the FaceTime share screen not filling the screen?

I recently updated my iPhone and iPad to the iOS 18 and when I join the share screen during FaceTime and zoom it to the full screen there is this grey bar that I can’t get rid of and blocks some of my view. I just want the old share screen back where it actually fills my screen in a comfortable viewing space. Even the new photos makes it more difficult to navigate. Can I go back to the iOS 17 when I didn’t have these issues?