In this link: "https://en.cppreference.com/w/cpp/language/character_literal"

You can find at the bottom of that page some abbreviation:

CWG 912, CWG 1024 and CWG 1656

What CWG means?

Thanks for reading)

CWG is an acronym for "core working group", a part of the committee that designs C++. Partly they maintain a numbered list of issues and defects in the design of the language itself (the "core language"). For example CWG 912 would be core language issue #912, this one:
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#912

The whole committee's website is
https://www.open-std.org/jtc1/sc22/wg21/

All the issues can be found at
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_toc.html

Amazing answer, thank you @mbozzi