I have seen that Hillary Clinton's pop vote lead grew as more votes were counted. For the first example, in a video by Fox News, Clinton won the popular vote by 1.7 million votes, and she won by 2.9 million when the votes were all counted. (This is not Fox being Fox, this is votes taking more time to count.)
They also become more left leaning. See that video from the Damage Report. It shows Bowman with a 24 point lead. As more votes were counted, the lead grew to 27 points and will likely grow further as more votes are counted from mail in.
This trend may have implications. An example is the NY-12 race. Carolyn Maloney is leading by only about 650 votes. If this trend persists and there are enough mail in votes, Patel, a progressive challenger, will win.
This appears to not just be US only, and seems to be related to the urban vs. rural divide. See "https://politics.stackexchange.com/questions/6240/why-do-late-counted-votes-tend-to-be-democratic-in-most-states".