It's (likely) not a bug... if the Soviets have 20 Weapons Factories, then they have 20 weapon luxuries, and they get +20 Combat Strength on home territory (while supplied).  There's been a lot of discussion about whether that's desired, but it is working as the game designers currently intend.

thanks guys for the reply, is there a way adjust this in config of the game?, game designers might be drunk at the time or they are from russia and they see all great and above all others from soviets