There are some terminals that turn on bluetooth without permission when the smartphone is restarted.
That's my CUBOT MAX.
This app is an app that just turns off bluetooth when the device starts up.

[How to use]
After installing, please restart your smartphone.
Bluetooth is turned off at the same time as startup.

※For smartphones with battery saving mode,
　Auto-startup and background services may not work correctly.
　In that case, Please allow it yourself from the individual app settings on the system settings menu.