I was investigating a problem with Brave completely locking up Ubuntu, random times from startup to having used it for a while. I found a recommendation to turn off hardware acceleration. So far that appears to be working. (Don't get me started on the problems caused by installing the tested proprietary driver, which was another recommendation.)
However, I also saw "Continue running background apps when Google Chrome is closed", which is on by default. I don't know about you, but this is yet another buried feature I would recommend turning off unless you really need it. (Applies to Chrome, Brave, Chromium, and likely any other browser based on Chrome.)
Paul