Malwarebytes extension would probbaly cause issues, Shields by itself will still block the detection (with the latest component update).
Many extensions (adblock/privacy/youtube-related) will cause issues with youtube, since the rules are updated daily and since these other extensions aren’t updated regularly. Brave and uBO get blamed for breakage or ads.
- Make sure brave://components
Brave Ad Block Updater
is the latest - Test in private window mode, no extensions.
- Clear cookies and cache and then relogin. (Important)
- Check https://drhyperion451.github.io/does-uBO-bypass-yt/
There maybe a delay when an youtube uBO update is out and when Brave gets it (around an hour).