Seeing ABNF meticulously spell out UTF-8 encoding is kinda funny but also seems really uncalled for lol. This is a technical standard for people, not input to code generation or something, just say "CHAR must be a single UTF-8 encoded codepoint per [UNICODE-REF]" or something and it'd be both more clear and significantly more concise

(Or, even better, just say "TEXT must be a UTF-8 encoded string" so you aren't allowing a bunch of ill-formed Unicode by claiming that text is just a string of standalone codepoints with no further rules or restrictions)