Couldn't find the thread about the 80% lowers, so my apologies.

On the PA PICS login website:

As of 12-16-19, the sale of partially-manufactured (often referred to as 80%) frames and receivers and kits which include the same, requires a background check through the Pennsylvania Instant Check System, in accordance with the Attorney General's binding opinion and applicable requirements within the UFA. No sales may occur by a licensed firearms dealer without such a check. PSP is not yet ready to process such checks and is working diligently to have a process in place as soon as possible within the next thirty days to allow these checks to occur in a lawful manner.