A number of observers have been predicting that, for a number of reasons, the youth vote--which tends to be fairly heavily Dem--may be significantly lower this election. The two usual reasons cited have been that 1) many students aren't at their colleges and are thus more difficult to locate and talk into voting, and 2) a general lack of enthusiasm for Biden.
Tonight RedState has two articles that confirm that trends in early voting do, indeed, have Dems worried.
Shipwreckedcrew writes in Early Absentee Ballot Voting in Some States Has Some Concerns for Democrats, quoting the United States Election Project:
Nick Arama seconds that view in Here Are the Metrics That Show Trump Has a Lock on the Election:
Both articles are worth a further reading, beyond these excerpts.