It was hard for unvaccinated players to keep it a secret, because there were different rules for them. That’s how Aaron Rodgers got outed. Baseball players were outed when they couldn’t go to Toronto games.
It would easy if the NFL permitted it and made an example out a select few to make everyone think the league was complying with the mandate.
It wasn’t, not for players.
And since it wasn’t, you wouldn’t expect the NFL to do anything to advertise that fact, would you.
I read recently about an athlete that had been caught with a fake vaccine card. So there’s that…