Both have ads baked in. Brave turns them off by default but tries to get you to turn them on and gives you fractions of a cent in crypto if you do. Mozilla has them on by default.

What ads does Firefox have?

Both have bundled things in their browser. Brave it was their VPN and affiliate link scandal. Mozilla was plugins like the Mr Robot plugin and changing people’s search engines to Bing without their consent when negotiating with Google.

The Mr. Robot plugin stopped being auto-installed a day after people complained about it back in 2017 (7 years ago), and I don’t think this ever happened again, while Brave still does its thing to this day (to my knowledge), I haven’t been able to find any info on that second point.

Both have made fringe political donations

Which fringe political donations has Mozilla made?

My guess is that sway checks sets the opacity when the window open, so when the first rule matches (app_id=.*) it skips all others, so maybe try putting the other 2 rules above the first one?

Sorry if my comment is incomprehensible, I’ve just woken up.

I don’t know about beefbot, but this blog convinced me to not use kagi:

Why I Lost Faith in Kagi