Also, the VA blowout has a huge impact for 22 in terms of who runs, and who doesn't.
No elected official likes to lose their way out of office - much better to retire and go out on a winning note, instead of the pain of being defeated at the polls.
And the thinking that it'll be a bad year for one party / good year for another keeps some on the sidelines, waiting for a better year (a loss or two under your belt and the stink of failure will doom your career), while those on the good year side can't wait to jump in and get while the goings good.
So I expect 22 to be a year where lots of sitting Democrats retire to avoid either being defeated, or having to work hard for the first time in years in an election. And lots of good candidates sitting this one out, waiting for a better year.
While on the Republican side - this will be the year people want to run, and are willing to give up safe seats at the state level to run for Federal office. All of which will increase the bloodbath a year from now.
Now the Democrats can still force Depends out whenever they want to - the Biden family is so crooked the FBI can be ordered to open a real investigation of them whenever it's needed to convince Slow Joe it's time to go. But I think they just bake a 22 blowout into their cake, and then bounce Depends out of office in 23, letting VP BJ to bask in the media glory of the HISTORIC FIRST WOMAN PRESIDENT!!!!
While the Democrat can certainly advance their rule when they control House / Senate / White House, they suffer no real back tracking when they don't control all three, or for that matter any of the three.
They still will have total control of the permanent government, and the Federal agencies are where the real power is, and are safely 95% Democrat staffed. A Republican congress will huff and puff and then fully fund every single Democrat program and NGO that was being funded before - they'll probably pass not only funding for Planned (Un)Parenthood, but give them a COLA raise to keep up with Biden-flation.