Login into Facebook, 2FA code sent to WhatsApp, I don't have WhatsApp. Bug or Hack?

Is this a bug or a hack? It doesn't feel malicious as nothing hackery is a foot. No one changed the password or made any posts or messages.

The only options I have it to stay logged in on one device ( laptop ) and use that logged in device to authorize other logins like on my phone. I don't have WhatsApp. I've never had WhatsApp. I'm not going to get WhatsApp.

Is this a Bug? Is there info posted anywhere? And how do I communicate my issue to support?

Thanks!