No need to be sarcastic. The problem of Soviets isn't so much a single unit but the combination of good units overall, which leaves Soviets with no disadvantage.
It comes down to the question of what makes a good faction? I would say the following aspects (I marked every aspect for the Soviets with school grades (A - F):
1. Cheap units
a) Upfront unit cost (Soviet units are amongst the cheapest in the game) A
b) Reinforcement cost (Soviet infantry is amongst the cheapest to reinforce, Elite inf is a bit more expensive) B
c) Do Upgrades have to be researched? (This is actually a weakness since Molotovs and AT-Nades have to be researched) D
2. Firepower
a) DPS (Soviet infantry maintains a decent DPS) C
b) Wipe potential (Best wiping potential in the game due to big and cheap guns, 120mm mortar, Zis barrage, good mines, T-34/85, KV 8, ISU 152, smaller Axis Squads) A
c) Range (two 60 range TDs, Soviets are good here) A
d) Artillery options (Best artillery options in the game, 152mm, 120mm mortar, B4, Kat) A
e) Flexibility of their units (the abilites are good on some units like the ZIS and bad on others like the T-34 capping ability) C
3. Durability
a) Large squad sices (Soviets have the largest squads and the largest weapon crews) A
b) High HP and armour on vehicles (Again, excellent grades for Soviets, KV1s that can take more hits than Panthers, a great performing IS-2 and of course KV-8s that can dominate Paks even midgame). A
Now where exactly is Soviets weakness? They EXCEL at cost, firepower and durability of their units.
I agree mostly but disagree on a few points.
In case off allies and soviets in particular their doctrinal units are always counted as if they where stock. That gives the false impression sov have no weakneses. Ost however docs are all but ignored. example ost squads are 4 men there for squishy, they have 5th men doctrinal option. They have auras to make them more durable and are rarely taken into account or at all. Keeping the premise of weak squads.
First their wipe potential/fire power.
The units u mentioned all doctrinal besides the zis. Stock sovs dont excel at wiping outside the t70 and katty. They lack nades and their dps being decent stock lowers wipe potential substationaly. Only doctrinal inf such as shock and gaurds can. Zis barrage ws nerfed to prevent one shot wipes.
Their mines are capped at 2 models per
squad. Since only the sniper is less then 4 men the wipe potential is very very limitid unles ost dont retreat/reinforce on time.
Durability/reinforce cost.
Their inf is more durable but they face more dps orented inf with powerfull nades. In both dps and nades sov are lacking compared to other factions, they have a
C tops. Sov also drop way more models then any other faction in the game. So their cost to reinforce are cheap to compensate. Unlike high armour with high hp you can always bleed with any gun but AT focused guns.
Sov only have high armour in doctrines. Wich until revently where used very little because they did very very lil damage got wrecked by at (old kv1) or missed so much it was irrelevant (is2/kv2)