That's the first I've heard of it and sounds absolutely insane.We can acknowledge that the Chinese Army suffered more losses than the Vietnamese.
Records from PLA state 6900 friendly KIA to 70 000 - 100 000 enemy. This is collaborated by 290 Chinese PoWs to 1630 Viet PoWs.
Remember, the side attacking into unfamiliar territory is expected to get captured much more.
It would be utterly impossible for Deng admin to cover up 100 000+ KIA. Even Mao admin with full national founding legend status didn't have enough cred to lie about Korean war numbers.
Besides there has never been a significant return of bodies by Vietnam to China. So if you claim PLA lost more than NVA in 1979 war, are you claiming that the conflict was much smaller than officially claimed and only involved a few 1000s on each side?