This is related to the device you are using and isn't an issue with the app. Make sure battery optimisations for the app are disabled.
Please go to this website and run through the steps to keep apps alive for your device: https://dontkillmyapp.com
If a toast message is appearing saying that an app is blocking the dialog, make sure you disable the Draw Overlay permissions for all apps before enabling the Accessibility Service.
If you cant see the app in the list, tap 'More downloaded services' or similar.
Otherwise, try restarting your device.
For some reason Google hasn't synced your purchase yet.
It usually fixes itself after you update your apps in the Play Store by tapping the 'refresh' button in 'My apps & games'.
Try Google Opinion Rewards. It allows you to earn Play Store credit which you can spend on apps.
Firstly, disable the Accessibility Service. Then restart your device. You should be able to grant the permissions now.
To stop this happening again, make sure battery optimizations are disabled for the app: https://dontkillmyapp.com
Android turns on DND automatically when silent mode is enabled. There is nothing the app can do to change this.
Unfortunately Android does not let apps change the auto brightness level all of the time. You can try enabling the "Allow changing auto brightness" option in the Advanced options, but this may not work due to Android limitations.
Long press the notification to hide it