How would that work, exactly?
PA senators are not subject to recalls, so it's out of the hands of the voters. He could technically be impeached and removed from office by the Senate itself... but for what, exactly? It's not illegal to vote a certain way, even if it's against the wishes of your constituency.
And even if Fetterman were somehow removed, PA is an extremely competitive state. Remember, he won against Doctor fucking Oz, so the chance of someone even worse coming in to replace him is quite high. The devil you know, etc etc...
Best case scenario is that he gets primaried into irrelevance in 2028 by someone with actual integrity. But even then, I'm not holding my breath...