Youd have to fill out teh Sch Se manually I guess. PS doesnt have a way to add SE tax to SE income without a Sch C.

Are you sure its subject to SS/Mdcr? PLF from the state isnt. Seems like if it was subject to SS/Mdcr it should have come on a W2.

Who paid this to them?

Typically, State would be 1099-G and that is treated the same as UI.

Employer would be W-2.

Third Party would be W-2.