As attractive as impeaching President Biden might be, and as well-deserved as it might be, a better option strategically might be to start with his power base. Going after Biden's underlings not only deals with problems head-on but may also be more achievable. Secretary Mayorkas is one such person, and increasingly, Merrick Garland is another.
Biden Impeachment
Biden’s Document-gate
So, why is this coming out now, long after the midterms? I think we know why. It may be because of the GOP's stated intention to investigate both allegations of Biden family corruption, and the "weaponization" of the U.S. government. Between those two sets of hearings, this matter would have been uncovered. The Democrats decided to control how this information got out and wanted to put their own spin it.