I just checked this and it’s indeed a bug in the keyboard firmware. It’s because Hyper changes Alt to AltGr. This is a leftover from when we had two Shift keys instead of a dedicated AGR key and needed an awkward way to generate AltGr. I will fix this in the upcoming keyboard firmware update.
To access the console in the meantime, you can press F3 in tuigreet (the text based login interface) and change the command to /usr/bin/bash. This gets you to the console after logging in.