The whole thing is unconstitutional because Trump is no longer in office, but the part in the Constitution that is relevant. Note that the party convicted will then be subject to criminal prosecution - that's a big part of the commie goal here.

Article I, Section 3:

Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.