I had missed this Votebeat/Spotlight PA story last week, but it seems to me it could be significant if it all comes down to PA:

Voters in most Pennsylvania counties will have the chance to fix errors with their mail ballots during this election and spare them from being rejected, according to a review of county policies by Votebeat and Spotlight PA.

Thirty-eight counties allow voters to fix errors with their mail ballots in some way.

The practice, referred to as notice-and-cure, is a policy some counties have adopted to inform voters of errors with their mail ballots that put those ballots at risk of rejection and allow those voters to correct the mistakes.

At least 26 counties, however, will not offer voters the chance to fix errors, according to the survey. However, in light of a new ruling from the state Supreme Court, counties will at least have to accept valid provisional ballots cast on Election Day by those voters.

The rules that can lead to mail ballots being rejected are outlined in Act 77, the 2019 law that expanded mail voting in Pennsylvania. It requires that voters place their ballot in a secrecy envelope before placing that envelope in the return envelope, and that voters sign and put the current date on the return envelope. Failing to do one of these things will prevent the county from counting the ballot.

Precisely how voters can fix these mistakes varies from county to county, creating a patchwork of policies around the state that can sometimes be confusing for voters and advocates to keep track of….