mine is doing the same thing, after installing i get that message about filesystem raw and it never boots it just goes to normal fastboot everytime, i tried doing the command fastboot erase userdata, and after reboot it still took me to fastboot mode.. where did i go wrong?
Have you updated your adb/fastboot? Older versions cant access fastbootd.
Are you in fastbootd when flashing? It has Fastbootd in red letters across the top.
Ignore the message when formatting data.