The Biden campaign is still claiming Russian interference while not denying the authenticity of the material. They city a letter from 50 or so former intelligence officials to claim the laptop is Russian interference, none of whom have any access to classified information now. DNI Ratcliffe says it's not Russian interference and no one (looking at Adam Schiff) has been given intelligence making that claim because none exists.
One is, there was a preexisting money laundering investigation that found out about the laptop when it was reported and grabbed it. This investigation could be about the Bidens, and everything has been kept quiet to keep the prosecution successful...
Two, it could be an FBI investigation into money laundering revolving around Rudy Giuliani, his alleged prior associate Lev Parnas, and other figures alleged to have been feeding information to Rudy of unknown quality and authenticity. We keep hearing rumors of some sort of investigation around that (it apparently flipped Lev Parnas; whether or not he's singing or composing remains to the seen). In this case, the laptop would be seized by the investigative team to protect their candidate and keep a lid on the information. The latter tactic would fit with an investigation that apparently produced nothing for about a year.
I have no idea whether any allegations against Rudy or his alleged associates have any merit. Ditto those against the Bidens, though the evidence in that case is certainly suggestive.