Someone asked about this:

https://www.politico.com/news/2023/09/12/trump-doj-assist-biden-impeachment-probe-00115393

The DOJ has no power over a process that exclusively belongs to the Legislative branch (impeachment and removal).

In fact, impeaching and removing a president was deliberately not given to the executive branch (for obvious reasons).

The part that is interesting is that this was what Trump's DOJ wanted when Trump was in the White House but the GOP would obviously ignore their own policies now.

Biden can mention it with a laugh.