This is major stability improvement introduced in version 2.0.2. Configured alarms are now treated the same way as any another alarms in the system (status bar icon, next alarm time on lock screen, etc.).
This is necessary due to the changes Android system made for the Doze (power saving) mode. By design Doze mode can decide to postpone any alarms configured in Android to the next maintenance window (which can occur tens of minutes after the configured alarm time).
To prevent this from happening, the only alarms that are not affected by Doze mode are those that are set into the Android system using the setAlarmClock method - these alarms continue to fire normally and system exists Doze shortly before those alarms fire. Alarms set by this method are tied to the UI elements mentioned above (icon in statusbar, information on the lockscreen - this is an Android system behavior), but they are the only alarms that you can be sure that will trigger at the specified time.
For that reason, from now on, all alarms configured by Mi Band Tools will be treated as default system alarms, otherwise there would be a risk that they would not fire at the specified time, which - of course - would not be desirable for alarms.
If you want to know more about Doze mode, please see Optimizing for Doze and App Standby Doze provides a recurring maintenance window for applications. Applications can not perform actions outside of maintenance windows.