The Blackview customization of the Android operating system is very aggressive about power saving. One annoying technique adopted is to prevent the auto start of almost all the apps installed. This has the visible and nasty consequence e.g. to not properly initialize at bootstrap some widgets that you may add to your home screen. I had problems with the Termux:Widget shortcuts, the Etar calendar and the SecondsClock widgets which were broken on each reboot.

Fortunately Blackview provides the System Manager app, where you can modify the list of the apps allowed for auto start (App Management ⇒ Auto Start Management).

Some apps, when launched, require other associated apps to be launched. You can enable this cascade startup using the App Management ⇒ Associated Startup page.

In Blackview System Manager you can also add some apps to the Auto cleanup exceptions, i.e. the apps that are not killed during the periodic automatic cleanup.

Last but not least, in System Manager you can go to the settings page (the gear icons) and eventually disable the Lock screen cleanup, which is responsible of the cleanup of the recents apps whenever you lock the screen.