It leaked early. Some think he was holding off because of the terms of his contract (02/04/22 is a key date), but it was going to be a headache until he said something. Someone in his inner circle did him no favors.
That key date thing is inconsequential. He gets his 15M regardless.
The announcement isn’t the paperwork. If he hasn’t filed the paperwork he’ll still be on the roster friday. Of course in his household it really isn’t that much money.
Probably someone in the White House leaked it. Probably the same person that leaked the Breyer retirement. They probably have an office under Psaki that is the Presidential Office of Misdirection - Retirement leaks, staffed by CNN and MSNBC on air anchors.