Based on exit polls, Biden won first time voters (14% of the electorate) by 32 points in 2020. First time midterm election voters (12% of the electorate) went to Republicans by 8 points in 2022. Though Democrats won the very small amount of 2020 nonvoters by 1 point. In 2018 Democrats won first time midterm voters (16% of the electorate) by 26. So something did seem to happen in 2022 that could presage first time voters being right leaning this time around. The timing is very odd though.
This change wasn't accompanied by a shift rightward with younger voters. This would be easier to accomplish in a lower turnout midterm. Still, that means that Republicans had to have won first time midterm voters who hadn't come of age in the past four years by *a lot* (like, 30 points).
I am a little surprised about Biden winning 2022 voters. Republicans won the house vote, so what, did Biden gain ground with these voters in the past 2 years? Doesn't seem likely. Meanwhile he does seem to be losing a small amount ground with the 2020 electorate (but not that much).
To add on to this point, Biden is basically sure to win the 18-22 year old first time voters who were just too young to vote in 2020 for Pres, and that group typically makes up a pretty significant share of first time voters, which is why these Trump + 20 numbers amongst first time voters either have a bad youth sample and/or have Trump winning older previous non-voters by like 40% which is insane.
