Brave's made a big mistake in the past, so I'd hold out on using it until there's no other non-Chrome option: https://www.theverge.com/2020/6/8/21283769/brave-browser-aff...
Seems like exactly what's needed in the context of the current situation, no?
Mozilla has had more missteps than Brave because it's been around longer. I can't name all the ones which betrayed trust, but the Mr. Robot scandal comes to mind:
https://www.theverge.com/2017/12/16/16784628/mozilla-mr-robo...
and:
https://www.ghacks.net/2017/02/12/firefox-focus-privacy-scan...
and:
https://www.reddit.com/r/firefox/comments/anxfz8/firefox_is_...
and many others.
Having said that, I still use both Firefox and Brave. It's ok to make missteps as long as you fix them and learn from them. Otherwise, I'd never use any product and never have any friends. No one is perfect.