I have reinstalled Brave browser and still no ads in days. Did a full purge, even installed it on a new system with Linux as well, I tested it so far on three machines, one of them being Windows and all haven’t displayed an ad in days from Brave.
Do you use a VPN? If so, it may be blocking Brave from refilling the ads catalog on your device. Try disabling the VPN for a few minutes, long enough for the ads catalog to refill. (You will know it’s refilling when a notification ad appears.) Then you can re-enable the VPN. If that starts the ads flowing again, you will need to refill the ads catalog about once per day.