Not all german tanks have muzzle brakes.
Main problem of muzzle brake - tank spotted by enemy after first fire. It's main reason why muzzle brakeremoved from Panzer IV/70, Hetzer, Jagdtiger, Panzer III with kwk 39 L/60 (same barrel than Pak 38, but without muzzle brake). Red Army have only one mass-production tank with muzzle brake - IS-2. Too powerful ammo for using without muzzle brake. Also muzzle brakes have SU-76 and SU/ISU-152, but reason is simple - they use ML-20 and ZIS-3 guns without recoil system changes.
Too big recoil power been main reason why late series M4(72)W, M36 GMC, late series M18 GMC and M26 Heavy Tank have muzzle brake on the guns.