Every time i fullscreen something, the entire browser goes fullscreen

This may be some config that i could’t find and change, but it annoys me so much. Every time i turn some video full screen on any website, the browser goes to fullscreen, and when i change it with F11, the browser kinda glitches.

Unfortunatly, i can’t upload videos here since i’m a new user, but i uploaded on Youtube and the link is here: https://youtu.be/Tco69DNTW6s
Please be patient, english is not my first language.

I use Windows 10 and the latest Brave version.

(I forgot to mute my microfone during the video recording, sorry for the scuff.)