On macOS 12.4, Monterey, Reader 22.001.20112 hangs immediately on loading. Beach ball immediately. I've reinstalled it and rebooted the Mac. New behaviour today. No recent OS updates or app installations that might explain it.
Hope you are doing well and sorry for the trouble.
As you have the recent version of the application, please try to reset the Acrobat preferences as described here https://community.adobe.com/t5/acrobat-discussions/how-to-reset-acrobat-preference-settings-to-defau...
Also try to create a new test user profile with full admin rights or enable the root account in MAC and try using the application there and check.
You may also go through the help page https://helpx.adobe.com/x-productkb/global/troubleshoot-system-errors-freezes-mac.html and see if that works for you.
Thanks, Amal. Manually resetting preferences did not help. Running the reader from a test profile was successful. Running AeroCleaner on the primary account seemed to resolve the problem. Back to normal thankfully, but without an explanation. File corruption of some kind somewhere, I would guess. Tony