Did all stug IV have zimmerit coating in World War 2?

Not all StuG IV vehicles were equipped with Zimmerit coating during World War II. Zimmerit was a thick paste applied to certain German armored vehicles to prevent the adhesion of magnetic mines, but its application was phased out by late 1944 due to production concerns and the changing nature of the battlefield. Consequently, while many early StuG IVs did have Zimmerit, later models produced towards the end of the war often did not.