| The jagdpanzer IV with the 7.5cm L48 had a muzzle break. |
Yes, initially.
"Originally the Jagdpanzer IV/48's gun had a muzzle brake installed, but because the gun was so close to the ground, each time it was fired, huge dust clouds would rise up and betray the vehicle's position, leading many crews to remove the muzzle brake in the field. Later variants dispensed with the muzzle brake."
Source: Wikipedia
Osprey's "Sturmartillerie & Panzerjäger" shows a drawing of a early Jagdpanzer IV of the Panzer Lehr Division (Normandy 1944) with the muzzle break removed:
