When backing up a machine with a monitor using logind to control idle timeout and things like DPMS, borgmatic can block the screen from turning on/off with systemd-inhibit. This is because by default systemd-inhibit will block "idle:sleep:shutdown". Borgmatic does not need to care about idle, only about suspend and shutdown. So, add an explicit `--what` flag for what borgmatic should inhibit. For more information see systemd-inhibit(1).