I can’t speak to Berlin, because I don’t have high-tier squads yet, but matches on Moscow, Stalingrad, and even Tunisia maps have been both well populated and well balanced.
But the game definitely has some sort of institutional memory of at least one of the campaigns, even if they are technically gone. Because playing as the Germans I can’t eke out a win to save my life on a Normandy map. It’s an absolute USA roflstomp of cartoonish proportions every damn time.
I’ve literally never deliberately deserted a match (I quit one or two when I had flipped factions without noticing before the session join and was like “what the heck?”), but I’m on the verge of just choosing to bail whenever I see a Normandy map.