I was using Brave on my iPad the other day and got a notice about this. It didn't seem to affect functionality though. Perhaps they will clamp down in the future, and this is just a warning.
I hope Brave can give me the option to make Google think I'm watching the ad by downloading the ad but somehow not showing it to me.
Or, failing that, show it but auto-mute the audio during the ad (I spent lots of time on Youtube listening to my playlist).