VA made a change in its election-administration policies after the 2020 election that I and many others had been advocating. In 2020, state law barred officials from starting to process must absentee ballots before polls had closed. This year, election officials are required to start that processing at least seven days before election day. To be clear, “processing” the ballots does not mean counting them; it means doing all the preliminary work to make sure the ballots are ready to be counted as soon as polls close.

This change might also lead to an inversion of the situation in 2020. If it turns out that Democrats again disproportionately makes use of absentee voting, then the early totals released initially — which will be weighted heavily toward the absentee vote — could favor McAuliffe. But if the election-day vote disproportionately favors Youngkin, those votes might get tallied a bit later in the evening.

The Washington Post has a good summary of the specifics here.