Mail ballots currently lean overwhelmingly Democratic and the party is likely to be disproportionately affected if thousands of votes are tossed out because of bans on grace periods for mail ballots in Ohio and elsewhere.

https://boltsmag.org/ohio-ends-grace-periods-for-mail-ballots/

Ohio Bans Grace Periods for Mail Ballots, Fulfilling Trump’s Wishes - Bolts

Ohio is the fourth GOP-run state this year to ban ballots that are postmarked by Election Day but arrive after. A Supreme Court case could force that policy nationwide next year.

Bolts