As others have noted, this is a legalese/formality issue (copied from ISO-3166), not a political statement. Note that IP ranges from provinces in mainland China are listed as "China", not "Province of China" (e.g. https://ipv4.dev.sarl/@zoom=16&ip=203.187.74.93). Additionally, the formal name of Taiwan is "Republic of China", so the loophole for formal purposes, as others have mentioned, is that the term "China" is ambiguous.

I think the more interesting thing is that Crimean IPs are listed as part of Russia (e.g. https://ipv4.dev.sarl/@zoom=16&ip=77.121.55.93). Practically speaking Crimea operates as province of Russia nowadays, but I believe formally/diplomatically most countries still recognize it as part of Ukraine. That's almost a reversal of Taiwan, which operates as an independent country in practice, but for formal/diplomatic purposes is considered as part of "One China".

Other than the standard people mentioned, there are also the "1992 consensus" [1] which intentionally made the word "China" ambiguous.

One possible interpretation is there's a thing called "de jure China", and both P.R.China and R.O.China (Taiwan) can claim themselves as legit. It's just de facto R.O.China happens to control only one province within China with is Taiwan (maybe plus some islands from Fujian).

[1] https://en.wikipedia.org/wiki/1992_Consensus

Related topics:

One China Policy: https://en.wikipedia.org/wiki/One_China

Taiwan Independence Movement: https://en.wikipedia.org/wiki/Taiwan_independence_movement

It’s in the standard that way: https://en.m.wikipedia.org/wiki/ISO_3166-1_alpha-2