Processing early is common
eg Florida
When Absentee/Mail Ballot Processing Can Begin
Upon receipt.
When Absentee/Mail Ballot Counting Can Begin
Upon the completion of the public testing of automatic tabulating equipment (which begins not more than 25 days before early voting commences). Releasing the results early is a felony.
This is why Florida is able to report most of their votes on election night.
If the election laws were applied equally and fairly throighout the state, this would be fine.
What happened in 2020 was nothing approaching equally applied and fair.
A lot of "nonpartisan" get out the vote money to sign up voters and do something similar to vote harvesting was distributed throughout PA, but largely concentrated in Dem strongholds.
Dem-heavy districts also contacted voters who screwed up their mail in ballot envelopes and allowed them to fix them ahead of time. This was against the letter of the law, but the law was ignored and poll workers permitted to contact the voters so they could fix their ballottes