Hello there @crypto.piotr.
How long have you be using Brave for? As I also did not have ads for about the 3 first weeks and now I get 10-20 per day. I have earned 5 BAT in a week just using the desktop browser.
They claim they redistribute in BAT 70% of the money they get selling ads.
Hope it is helpful and as commented above, I also wrote a post about it a few days ago.
Cheers,