brcm-patchram-plus appears to be installed in the images for some reason but not enabled. The dependency in rpi4-post-install will be removed in it’s future package release. brcm-patchram-plus willl be the default service for bluetooth in the future. This expanation is in a nut shell. Full explanation was posted here:
brcm-patchram-plus-conflict-with-pi-bluetooth
For now for the 3b+ & 4b devices only:
sudo systemctl disable brcm43438.service
sudo pacman -S -dd brcm-patchram-plus firmware-raspberrypi
sudo systemctl enable attach-bluetooth.service
For now for the RPi’s pi 400 device only:
sudo systemctl disable brcm43438.service
sudo pacman -S -dd brcm-patchram-plus-pi400 firmware-raspberrypi
sudo systemctl enable attach-bluetooth-pi400.service
For now for the pi3b device only:
sudo systemctl disable brcm43438.service
sudo pacman -S -dd brcm-patchram-plus-pi3 firmware-raspberrypi
sudo systemctl enable attach-bluetooth-pi3.service
Reboot for the new bluetooth service to be picked up.