Aside from BMPT’s being prime example of a already overperforming vehicle receiving artificial survivability buffs (6mm of rha that doesnt spall, fake external belts etc.) you also have many hidden platings on russian mbts that absorb spall, such as the 2mm of structural steel on T-64 and T-80 autoloaders; (sufficient to absorb spall, same thickness as horizontal-drive modules, but armourThrough value too low to create spall)
The autoloader module itself also does not create spall either, yet can absorb it aswell.
Hidden 45mm mCHA (0.98x RHA) gun cradle (on chinese mbts it’s part of the trunnions);

Present on all T-64, T-72, T-80 and T-90 variants
Trunnions being a demented artificial survivability buff and a major cause of shot inconsistency: (remember that the inner barrel diameter is 125mm… Is anyone going to act as if not a singular part of the russian mbts’ trunnions is thinner than 150mm?!)

^ every part of this is modelled to be AT LEAST 150mm of mCHA (0.98x RHA) and up to 300mm effective.
Then again Trunnions should be removed from every vehicle to begin with, just that their dimensions and effective armour are the most absurd on T-Series mbts
Or other changes that aren’t announced nor have any sources provided for them (thank god datamines exist so these changes arent entirely hidden):

Or here’s them randomly deciding to make it significantly harder to overpressure T-90M:


(if you understand how overpressure/pressure damage works in this game, then you should also understand just how significant and stupid these two changes are).
And ofc there are also Contact-5 and Relict casually auto-destabilizing the best APFSDS rounds in the game at any angle and distance, reducing their residual penetration to such a degree that their damage (fragmentation count, amount & penetration) can become nearly non-existent - aswell as heavily affecting their trajectory.
The destabilization effect of the Relict/Contact-5 tiles on the skirts is also 5x higher than that of Duplet, despite Duplet having either the same (relict) or significantly more (contact-5) listed KE equivalence.
There are several other examples to bring up but I believe this to be sufficient to illustrate what I am trying to convey.
This is a quote from one of the people here on the forum he did a GREAT job explaining some details of russians being buffed.