I blocked my first plane when this was first available, blocked my current plane before I even flew it home, always at the FAA source level.
Now the problem is the tech, that ADSB or mode S is broadcasting in the clear, so it’s only blocked on the more official tracking sites who care about what the FAA requests.
Anyone with a couple hundred bucks can put a tracker anywhere that will track anything broadcasting 1090/978,

and if they so choose they can upload that data to sites that don’t care if you
ask to be blocked or not on sites likes this
https://globe.adsbexchange.com/ Blocking is good, but the real solution is a ADSB box that sends N0 for a tail number when set to 1200, there are a few that do this, think the tail beacon does, of course that also doesn’t work if you’re on a code. Just goes to reaffirm the S in ADSB doesn’t stand for safety