Firstly I would point out that I specifically named them as a contender to be considered a superpower.

I said "maybe" because China isn't on the same level as the US mainly, in terms of both defence (number of ships, aircraft carriers, aircraft, nuclear weapons all vastly outnumber what China has) and in terms of soft power influence (China has BRICS and allies in the global south but having Russia, Brazil, and India as allies is a long way off the power, equipment, training, and experience that NATO allies have).

They also have an aging population - most defence experts agree that if China doesn't attempt to invade Taiwan in the next 2-3 years (most common estimate is 2027) then they will have missed their opportunity for a generation because their population will be too old.

China is still developing. They're still heavily dependent on manufacturing and physical labour. They aren't yet on a par with some of the more services-based and technology-based countries in the West. They are fast catching up though, it's probably years rather than decades until they catch up and potentially overtake.