I guess I’m not the first one to notice this, but here is how to reproduce the problem:
In Brave browser on Android, go to youtube and start playing a video
Maximize the video to watch in full screen
From then on, the cog button giving access to settings such as play speed or captions doesn’t work anymore, you have to demaximize/exit full screen for the cog button to work
Yeah, we discussed this a few days ago internally, it occurs in Chrome also. What I believe is happening the cog menu is showing, but in the background. Not much we can do here, best to adjust your settings before going full screen.