In `/etc/pipewire/media-session.d/bluez-monitor.conf`, I uncommented:

    bluez5.msbc-support = true
    bluez5.sbc-xq-support = true

You'll also need to make sure you're on a kernel supporting the WBS fallback patch[1], which should be the case if you have the latest 5.10 kernel or the 5.12 development kernel.

You can check if it's working by running `info all` in pw-cli. It'll mention if the bluez codec is "mSBC".

[1] https://patchwork.kernel.org/project/bluetooth/patch/2020121...