The FEC would designate those funds as campaign donations.
The FEC would charge Trump with campaign financing violations for using campaign funds to pay private fines.
The FEC already tried to do that with Trumps payment to Stormy Daniels. They deadlocked with a 2-2 vote. They would certainly succeed this time.
I think this is what the Left really wants... to somehow draw into question how Trump got the money. This way they can make accusations about his use of funds resulting in fines or jail.
And if they’re successful with seizing Trump’s assets, Elon Musk will be their next target going after Tesla and SpaceX.