Pz.III E Armor issues

The Turret on the panzer 3 E has 30mm on the front of the turret when it should have 35 was this intended for balance or a mistake made by the devs

I think Pz3e has 30mm but i could be wrong

The inner gun mantlet has 30mm of thickness while the outer part of mantlet and turret front armor has 35mm and 37mm around the gun.