Stop using the Solo launcher and use one that doesn't do that in Android 8. A lot of us here have found
Nova Launcher to be a good one. (And with the 3 screens full of apps, it's
never added on on its own.) Of course, make sure that, in Settings, you don't have "automatically add new apps to home screen" turned off. An update to an app is a "new app", as far as that function is concerned, so every time an app is updated, if that's on, it
will appear on the home screen. That alone may be your problem.)