I wanted to point out another weakness of the Harris Campaign.
One of Biden's big talking points was the cancellation of student loan debt. I think many younger people were mobilized and ended up voting for something that would actually affect them personally. Biden ended up failing to uphold his promise for mass cancellation of the student loan debt. Harris couldn't talk about it, and didn't have a talking point nearly as strong as that. Not only was trust in a democrat president eroded, but also trust in any president since the Republicans were clearly against the cancelling of student loan debt. Thus, turnout ended up worse.
I think the next candidate needs to come up with another impossible promise like that to get turnout to be as great as it was in 2020.