Or they just weren't particularly motivated to show up.
Trump got 1 million votes more than he got in 2020, and Harris got 9 million less than Biden but there's probably about 4 million votes outstanding on the west cost that haven't been counted yet, so let's say for argument that those numbers are likely to break 2 million more for Trump and 7 million less for Harris.
Part of that is that states scaled back on vote by mail.
Part of that is that without the threat of Covid/Riots/Recessions, people were less motivated to vote if their lives depended on it.
A large part of that is probably because if you didn't live in one of the seven swing states, there really wasn't much point to voting.
It appears that slightly less white people voted for Trump, and black people were about the same. Where Trump made gains was with Hispanics and Asians, particularly men in both those demographics, which is understandable, they tend to be a lot more patriarchal.