There has been a lot of discussion on several forums about HMD's Evenwell apps causing battery drain and stopping apps running in the background. A number of solutions have been proposed to disable or remove these apps including using ADB. One solution uses only the phone's settings menu and is easily reversible. It is this method i am documenting below.
Open the settings menu and tap on Apps & notifications/see all apps. Then tap on the overflow menu (3 dots in upper right corner) and tap on Show system. You can now access the required apps.
For the following apps, tap on the app then tap on Advanced then tap on Modify system settings. Then set the toggle to off.
For the following apps, tap on the app and then tap on DISABLE.
These apps are now effectively disabled.
The Battery saver app is the one that stops apps running in the background and the others modify Android One Pie built in power saving routines for the worse.