Knowingly using a private API without authorization can fall under CFAA, contract law, copyright law, trespass to chattel, etc -- and you can issue a C&D and/or sue for whatever is relevant.
https://en.wikipedia.org/wiki/Goatse_Security#AT&T/iPad_emai...
https://www.praetorianprefect.com/2010/06/114000-ipad-owners...
And CFAA is limited by Van Buren.
Calling it illegal is utterly insane. It’s just a different user-agent and they’d prefer people use their official ones. OpenAI literally controls the keys so if they don’t want someone using an alternate mechanism, they can and will just ban the account.
If someone bypasses authentication I understand but if your api is open on the public internet on purpose, you don't get to randomly declare what's private and what isn't.
Whoo whoo, go easy on the straw man, man.