No, I don't have access to Sub Zero from before the patch, but I can compare the damage of his known combos with its current damage tho.
Combos below was taken from the Sub Zero combo thread, which was said to be done on Superman with competitive mode on.
J2, f22xxexIB, b3, j3, slight walk, 33xxPP. Deals 41% dmg -> now 39%
J3 (cross-up), 33xxexPP, b3, j3, f22xxPP. Deals 45,5% dmg -> now 43%
J2, b23xxexIB, b3, j3, slight walk, 33xxPP. Deals 42% dmg. -> now 39%
Seems like Sub's damage is indeed nerfed with only 20%-30%.
I don't remember what character I used as my training dummy before the patch, but it was probably someone with a lot less defense, which is why the damage difference seemed a lot bigger than it actually was.