I'm not sure why Harris waited in contrast - especially given there is to be no farewell speech. Maybe there were lingering concerns she might be called back to vote on election-related matters?
Yeah, I don't know why she waited so long. I get that making sure Congress certified the Electoral College was vital and she shouldn't have resigned before January 6th because of Trump's antics.
However, after the election was certified on the 7th, I thought that she would have announced her resignation soon after.