You noticed this too? ;-)
I went and looked up the “Mother of All Bombs” on wikipedia. It is specified as an 11 ton explosive yield. So unless this puppy is nuclear - it isn’t going to be 200 to 500 Ktons!
A nuclear warhead is a well known method of destroying an aircfaft carrier group. China just came late to the party and the journalists are all excited.
For example, this is an interesting video. BrahMos, in this video, is not supposed to carry a nuclear payload. The weight of the payload is specified as up to 300 kg. But if you look at Moskit which is officially nuclear-capable you read this:
320 kg (710 lb) explosive or 120 kt of TNT fission-fusion thermonuclear
Now, how hard would it be to mount a 300 kg warhead onto a 300 kg capable missile? Is it even conceivable that nobody in the long chain of generals, Russian and Indian, ever asked that question? IMO, BrahMos is advertised as a conventional weapon only because it's an international project. Everyone understands that you don't use these missiles against fishing boats. (But you can; look at the accuracy in the video.)
The new thing that China did here is simple. They used a ballistic missile, and as I understand it is minimally controlled in the descent phase. Its defense is only in speed, and in hope that it is correctly aimed and the target does not move appreciably fast and that the target does not shoot at the incoming missile with everything it got. This may be a valid approach, or it may be a flawed one. Without a test in battle conditions it's hard to say; after the test the survivors wouldn't be very interested in such trivia.