Not that I trust mail in ballots, but there is alternative explanation.
Many Republican voters do not trust mail ins. They either vote on election day or drop their ballot on election night.
This is actually quite a long trend in AZ.
So first counted in AZ are the Democrats and the moderate Republicans. Ultra MAGA are (will be) counted last!
One day to vote fixes all the problems. Make it a national holiday if you need to
That’s what I do. I haven’t trusted the USPS with my ballot since 2004. I like filling out the ballot in the comfort of my home and then dropping it off at the polling location on Election Day.