Right now all of the proposed questions are so bonkers that many people will get parliamentary elections ballot and ignore referendum. EU accession referendum is the only referendum ever that met quorum in Poland so putting that question on a ballot could potentially mobilize people.

PiS won't do it because their long term plan is to sow enough distrust to EU that they would have to "begrudgingly" leave the EU in a couple of years. They don't need a referendum for that either - previous government (led by PO) passed a law so that only a parliamentary majority is required for that IIRC.