On April 8, the Pennsylvania Supreme Court issued an opinion in Re: the Nomination Petitions of Rania Major, 15 EAP 2021. It holds that a signature on a petition is invalid unless the signer lists the address at which he or she is registered. Here is the 13-page opinion.
A few years ago the same court came to the opposite conclusion, but in 2019 the statute was amended. The old statute said signers should show their “residence” address on the petition. The new law says they should show the address at which they are registered.