Take this with very large grains of salt folks. The Russians have been making claims like this for many many decades. It wasn’t long ago they were bragging about nuclear powered weapons.
And, after several months of hype with no proof whatsoever they had actually accomplished this the program was quietly scrapped if it ever actually existed at all.
Agree. Maneuverability at high speed tends to take a severe toll on accuracy. If the target is hard that toll may mean a weapon expended to little or no advantage.
Just a few weeks ago their one and only carrier caught fire while in dry dock. The same carrier that a couple of years ago had to turn back not even halfway to the Med for a planned cruise.
I doubt they can even put twenty ships to sea at one time. And a Mach 20 missile? Wouldn't that be a quantum leap in material / propulsion / guidance? I mean, stranger things have happened, but again, I'm skeptical.