After installing the Manjaro [Stable Update] 2022-07-18 update, i lost sound from my MOTU M2 USB AMP/DAC. This was a result of one or both updated files, alsa-lib 18.104.22.168-1 and alsa-ucm-conf 22.214.171.124-1.
In my case i'm running Manjaro and pipewire, however i'm not sure the issue is specific to pipewire, Manjaro or the MOTU M2. I suspect the solution that worked for me may work for other configurations since the problem was present in other distro's when i tested with a live USB.
For Arch-based OS's you can install the downgrade package from the AUR (the AUR package will avoid the "Downgrading from A.L.A. is disabled on the stable branch" problem which is apparently specific to Manjaro).
Next, downgrade alsa-ucm-conf from 126.96.36.199-1 to 188.8.131.52-1:
$ sudo downgrade alsa-ucm-conf
Power on/cycle the DAC (a reboot may be necessary, or restarting the sound subsystem). If that doesn't solve the problem then try also downgrading alsa-lib from 184.108.40.206-1 to 220.127.116.11-1:
$ sudo downgrade alsa-lib
I wouldn't suggest placing these packages in the ignore list since this could break future updates if you forget about them. Instead you could just re-downgrade them after an update if necessary, however i suspect the problem in alsa-ucm-conf may be fixed pretty quickly.