As a meta note: It is really interesting watching last minute attempts to do things in a 4 year administration which thought it would have 8 years. Like splitting Chrome from Google... the next administration will probably just gut any attempts to punish these monopolists.
It's not certain the next administration will stop the attempts - remember that tech companies are "woke". Musk's companies certainly won't be probed, but Microsoft and Google will probably be offered deals that involve certain restrictions on speech for dropping the probes.
Biden was asleep at the wheel for a large majority of his term (a fact criminally hidden by his handlers and enablers). When he was awake, he was campaigning and fund-raising. I'm not surprised at his 11th-hour initiatives.