Harris is leading in the polls in all the states she needs to win. Moreover, she's leading in the polls there by more than Trump is winning in his must-wins of NC and GA.
Sure, a systemic polling error could mean Trump wins, but a few things. First, there's no a priori reason why polls should favor the Dem over Trump. That has been the case in the last two elections, but the effect has been attributed to factors that pollsters can adjust to and which depend on malleable human behavior being constant. Second, the proliferation of red wave polls, factored into the polling averages, makes it less likely that the polls will be tilted in Harris' favor. Third, if there has been meaningful change in the electorate, then it could disrupt polling accuracy.
I keep thinking about all the people who died from Covid post-election in 2020. They were predominantly Republican. They were also disproportionately anti-vaxx, pro-conspiracy people -- exactly the sort of person who didn't really vote much but Trump turned out. Well, Covid caused a lot of death, but not that much as a % of the population. Still, in a state like WI, 10,000 missing Trump votes could make a difference.
I also suspect that sorting will be a factor. States like MI, PA and NC had more "liberal" masking/Covid policies. I would imagine that people offended by that would be more likely to move out of state than people with more balanced views, and if they did leave, it would have been to freedumb states like Florida or the like.