In CoH3, Relic replaced this with -50% received damage, which leads to these immersion breaking scenarios where squads can eat a nuclear explosion to the face
This is not true. Squads in CoH3 cant eat nukes, most tanks still one shot retreating models unless its a LV\light tank. Airstikes\Call-in arty\flame also reliably kill retreating units.
On the other hand -50% damage reduction makes retreating squads almost invulnerable to bolt-action rifles, standart nades and even SMG squads have to pretty much camp retreat path to wipe squads. And if retreating squad has more then like 10% health\2 models you might not even bother trying to wipe it with inf, aswell as if squad is retreating from face to face engagement.