"fastboot reboot fastboot" boots into TWRP, not fastbootd
I am trying to reinstall Oxygen OS on my Oneplus Nord N100, and you need to boot into fastbootd or else it will say cannot flash critical partition. But, the command to do so just boots into TWRP.
In fact, in the TWRP Reboot menu, if you click on the "fastboot" option it just restarts TWRP but you cannot tap on anything. I am very confused, also I cannot use my phone because no OS is installed. I tried looking it up, but it seems it hasn't happened to anyone else.
I think it might have something to do with having no operating system so it boots into recovery automatically. Because when I turn on my phone it automatically boots into twrp, but I don't get why it does that for fastboot.
Did you tried run the command:
fastboot flashing unlock_critical
and then flash through fastboot instead of fastbootd