Shortcuts App (iOS 13.1.2): How to prevent that the shortcuts app interface opens, when you start a shortcut from the homescreen?
The only way to prevent that is to use the Shortcut "widget" instead of using a shortcut from the iOS home screen.

By "widget" I mean that screen which appears on the iOS home screen (aka "Springboard") when you are at the first screen of apps and then swipe from left-to-right.

Scroll to the bottom and tap 'Edit'

In the "Add Widgets" screen which appears, select "Shortcuts"