Block the account whose tweet is being promoted, and/or the account promoting it (sometimes there will be tiny text saying "promoted by"). You'll never see tweets from that brand again, whether promoted or unpromoted.

After a few weeks of this you'll get some pretty strange tweets from really obscure brands. You will however still regularly see promoted tweets from financial services companies, because there are apparently an infinite number of them.

Yes, so that Twitter in their algorithm figures out that you can't consume this particular ad, it finds others. The more you block, the smaller the pool of advertisers is.