SPB did not participate in any of the post-election litigation, so far as I can tell. Trump’s ambassador to Luxemburg joined the firm sometime in the past few months, made an appearance in the attorney fees dispute last month, and fixed the situation by paying off the paltry amount of fees claimed in the motion. It’s highly unlikely that it was personal or firm money, and it’s incredibly unlikely that any of it would have been permitted to happen if Trump had any unpaid bills with the firm. Big Law does not work like that.
Notably, SPB was where Michael Cohen set up office space for a time when he was trying to cash in as a lobbyist after Trump entered office. It led to them getting hit with a search warrant, IIRC. Why they would want to get tangled up with TrumpWorld again is a mystery to me.