"The court unanimously decided to set aside undated or incorrectly dated mail-in ballots. Under Pennsylvania law, mail-in voters are required to sign and date a declaration on the outer envelope. Despite this requirement, if undated or incorrectly dated ballots are turned in on time, they are eligible to be counted."

https://www.breitbart.com/politics/2022/11/01/pennsylvania-supreme-court-orders-election-officials-to-set-aside-undated-mail-in-ballots/