I think I’ve narrowed this down to YouTube videos. I’ve found another Brave user with the exact same issue - he just stopped using Brave, which seems drastic, but the bug is very intense and hogs resources to the point of people doing drastic things, so I get it. The real mistake is being in maximized mode if it hits - very little one can do to get out.
I believe that the browser basically becomes non-responsive to keyboard input, so it cannot be gotten out of maximized mode by the Escape key, and then the browser does two things after the user does something like a power-button exit, or can manage to use tricky methods to get a logout (very hard), if user settings are to restore last pages: (1) resumes on the same toxic YT site, and (2) resumes in maximized mode. Without access to the menu, there seems to be no way to get out of the maximized state - even F11 minimizes, but does not demaximize.
So to test this, just go to YouTube videos with Linux Brave and start viewing a video of about 45 min or greater length and see if you get a resource-hogging state - preferably with settings prepared to NOT restore last pages and do NOT go to fullscreen unless that is needed to initiate the bug (I don’t think it is). I don’t think the particular video is important, but size may be - try a 45 min or longer one. I am debating whether to try to get an exemplary URL - I just got my Brave back, and I’m in no mood to go through that stuff again! YouTube is off the menu for now.
I will say this, though - I am SPOILED by Brave. The non-integrated ad-blocking of the other browsers, and the SPEED and SIMPLICITY of Brave are very obvious after not using these others for a while (Firefox and Chrome).