The signature of the QR code would need to be accepted by your mobile, not the public computer. I don’t think mitm the QR code process is possible if they sign

The signature of the QR code would need to be accepted by your mobile, not the public computer. I don’t think mitm the QR code process is possible if they sign it. But if the public computer is compromised, anything you log into from that computer is accessible by the attacker anyway, as long as the session is valid.