To be successful, it had to correctly deal with every nuance of the printf spec. cppreference got a couple of these incorrect wrt to modifiers. Not something a routine user would notice, but a pedantic one would. (Sorry, I don't remember exactly what the mistakes were.)
I still use cppreference because it is so dang convenient. But I don't rely on it when perfection is required.
It's really too bad that copyright forces everyone writing a manual to rewrite & rephrase things. I wish the C++ Standard was online.
One online reference I dearly like is https://www.felixcloutier.com/x86/index.html which has saved me so much time. But it was created by scanning the actual reference manuals, so barring scanning errors, it is exactly correct. I gave up using reformulations of the CPU instruction set long ago, they had too many mistakes.