Writing for Politico, Seth Masket makes a point I haven't seen elsewhere explaining the atypical outcome of the recent election. He concludes:
Republicans are understandably disappointed by the election outcome this year. But one of the core reasons is they secured a huge policy win, one that they’ve advocated for nearly half a century. And despite those self-imposed headwinds, Republicans still took the House, albeit narrowly. If that’s the cost, the GOP arguably got a good deal.
The "huge policy win" he refers to is the Dobbs SCOTUS decision overturning Roe v. Wade. The red wave outcome we expected would still have left Joe Biden as President in place to veto Republican policy initiatives. From that perspective, the lesser outcome we got isn't bad.