The most common reasons for your DUH app to stop working all together is that you are not online, you don't have your settings enabled or your phone has shut off the service that controls your device. (This is very common with android 10+)
Double check to make sure you went online with DUH. Check and make sure that your auto accept and/or auto decline is enabled and setup correctly. You might also check that your DUH is up to date, to do this go to your DUH account screen > check for update.
If you have the red banner in your app that tells you that your accessibility services are not working or you just believe the are not working because the app isn't functioning, then you will need to reset them. Typically a reboot will fix any issues, but if not you will need to manually redo the permission.
Phone settings > accessibility > installed services > drivers utility helper (toggle the switch off > back on > reboot device)