-
Don't think you can block them. They're not separate adverts. They just annotate activities that someone has done on Sufferfest/Zwift/etc with a few extra bits. Here's an example from my feed:-
(So the only bits that are new are the "Sponsored" bit in the top right of the image, the name of the company bottom left and a "Learn more" link bottom right.
The new setting only turns it off for your own activities you do with sponsored integrations. It doesn't change the ones belonging to others that appear in your feed.
Minor really, but could be the start of the slippery slope.
pi-hole.net is my new favourite thing though I don't use Strava often enough to know what effect it will have on it.