Interesting, whereas I have absolutely no ads or issues on YouTube. Not sure about other sites you’re mentioning. But everything has been good, especially on desktop. I know you’re usually on things @CerealLover but let me ask out of curiosity, had you tried recently to Clear site and shield settings from brave://settings/privacy?
I do recall a little while back someone who had issues with YouTube and once they cleared that, it went back to working properly. Otherwise, I know Fanboynz usually suggest the below: