anonymoushn parent
It replaces them with different numbers, even if you don't try to do math on them :)
While I agree that the meaning of json numbers exists, I'm not sure which JSON standard you're referring to that contains this meaning. json.org certainly does not contain it, and links to ECMA-404, which just says "JSON is agnostic about the semantics of numbers."
jq tries to preserve number precision if you don't do operation with them, but as you noted this is within some sanity. If you do operations the involved numbers will first be converted to binary64 (aka double), same as node and most other languages. This is what is recommended by RFC 7159 for interoperability.