And Brave's built-in blocker uses uBO's and other lists, including allowing trusted filters (which can inject high risk scripts into your sites) automatically. So yes, you are using 3rd party scripts already, and no, they can't monitor all of the commits from all those lists.

The first party developer in case of Brave is arguably worse than most 3rd party developers elsewhere.

I would argue that third party developer is more reliable and trustworthy than both Brave and Mozilla