Today I got a rpi4 8g.
While I have played a lot with raspberry pi - it seems there has been a change to the accepted format of the sd card.
I downloaded the Manjaro sway version - I really don’t think this matters - and wrote the image to sd. (used both dd and gnome disks)
Then I ensured the image was correctly written by safe ejecting and syncing before removing the card from pc.
I got 4 green flashes followed by 4 more in a doubled rate - and from raspberrypi web I found this means unsupported board?
I then installed rpi-imager from AUR - which I used to flash the official raspberrypi os - and then I could boot the board.
What is the difference - I have no idea - can anyone shed some light on this?