I read somewhere that there was a clause in the law passed by the PA legislature allowing for mail in ballots that stated if any of the conditions in a list of sections in the law were changed or invalidated that the entire law was invalidated. One of those sections was the requirement that all mail in ballots must be received by 8 PM on 11-3-2020. Since the PA Supreme Court changed that section, according to the law, the entire law allowing for mail in ballots should be invalid.
But where to find that now I have no clue. Here's a link to Act 77, the law in question.
Section 11 of 2019 Act 77 reads:
“Sections 1, 2, 3, 3.2, 4, 5, 5.1, 6, 7, 8, 9 and 12 of this act are nonseverable. If any provision of this act or its application to any person or circumstance is held invalid, the remaining provisions or applications of this act are void.”
The whole Act is here:
https://www.legis.state.pa.us/cfdocs/legis/li/uconsCheck.cfm?yr=2019&sessInd=0&act=77
Thank you, someone already pointed me to the clause in question. :)