@xgrxx The notifications are likely Brave Rewards. Though to get them, you would have had to enable it. Brave Rewards is where you can allow notifications to appear. If you link the Rewards to a custodial account such as Uphold, then you can earn BAT for each ad you see. If you have no idea what all of that is but you are using the browser, I’d quite shocked.
https://support.brave.com/hc/en-us/articles/360018123651-How-do-I-use-Brave-Rewards-
https://brave.com/brave-rewards/
Then I have a brief little FAQ thing on some of the bits around Rewards that you can see at the links below: