Is canonilization not irrelevant. Any format with comments is not canonical; so xᴍʟ is not, ᴊꜱᴏɴ has escapes options for string characters so it not either.
Almost no serialization format is canonical by default---AFAIK bencode was the sole example that mandates the canonicalization. Instead, a canonical subset of the format is usually defined, which would of course exclude comments, unless comments themselves are considered semantic like XML. Yes, even XML has a canonical subset [1]!
[1] https://www.w3.org/TR/xml-c14n/