The difference between what Russian tech is “supposed” to do and what it actually does has been, historically speaking, significant. I’ll believe this if they manage to credibly get one single munition past a Patriot emplacement or past Aegis. Until then it’s all talk.
Any statement preceded by “no source needed” is propaganda.
I don’t even think you’re wrong here, but that’s not a statement that should ever stand unchallenged.