Another theory too is that, because of COVID and because so many people were impacted / stuck inside during that period, raised the salience of politics a lot more in people's lives and drove insane turnout that is likely not to be replicated on either side in 2024.
I would be shocked if either side turns out as much as they did in 2020, so setting aside persuasion (it does matter to a degree) and registering new voters, the ballgame comes down turning out / motivating as many 2020 voters as possible to get back out again in 2024. On that front, there's more work to be done, but I think that Harris is on the right track from what I can see