could you update your brave and see if it has the same issue and if it did not work could you go to brave://settings/system and disable hardware acceleration
if all of that did not work then what is linux dist and version?
Thank you @justsomeone1 - my distro (Manjaro Linux) didn’t provide a 1.20 package yet, so I upgraded to 1.20 by using the binary build directly - and the issue seems to be gone now.
By the way, I tried switching off hardware acceleration before and this solved the issue, too - but watching videos was terribly unsmooth after that.