FWIW, I accidentally upgraded my Ubuntu Raspberry Pi 4 off of the 20.04 LTS release and to 21.04 and had issues with my FTDI devices (mount and focuser). I tried 21.10 to no avail, and saw that there public discussions of similar problems. I was unable to get things working, despite trying for a few days. In the end I bit the bullet and "downgraded" to 20.04 LTS (by downgrading, I really mean wiping the machine clean and re-installing everything). Things are working again.
If you have FTDI devices, I would be cautious about going to those releases on RPi.