There was a patch recently that nerfed Heavy Tanks and buffed ATGMs. It also increased the range on select Mediums, like Super M60, AMX-30 Valorise, Kpz-70, and T-64s. Last patch the Heavy Tanks were way too good.
There's a new game mode: Conquest. It's like domination-style. Bases are less important. Whichever team controls the majority of control points, wins right away.
Heavies wern't nerfed, they were only buffed. Just not as much as ATGMs, which russian heavies have anyway.