Which shows that Russia knows the Su-57 is junk.
The Su-57 radar signature is not stealthy because Russia has not figured out how to launch missiles out of a weapons bay.
Even when (if) they figure out the internal weapons bay, it still has 1000 times the RCS of an F-35. The Sukhoi would never see the 5th Gen fighter that shoots it down, and it is vulnerable to modern air defense systems at 6x the distance of a true stealth fighter.