At worst, it's just fine (Mozilla just uses it internally to replace or supplement its old and incomplete Tracker Blocking system, which never gets the same scrutiny).
I think you're right but I'm sure they can fuck it up a lot worse than that if they really want to. AI ad detection? Sponsored blocking? New RCE pathways?
I think its much more likely than not a step forward, and I welcome the change, but recent Mozilla decisions have me watching closely.