Why do you think there is a bug? I am no expert, but I understand WPA2 TKIP to be compromised. I thought KRACK was the end of WPA2 being considered very secure. It seems the warning would be valid especially when WPA3 is an option.
This is surely an iOS bug. I don't think WPA TKIP / WPA2 / WPA3 is even a legal transition mode. I don't see any sign that 27.3 is broadcasting a network like that -- might be worth packet capturing a few beacons.