Modes and routines Samsung S23 UI 6.1

[Trackdayrider]

Can someone explain why I can't setup a routine that on receipt of a notification from an app (calendar app in this case) that allows me to change the wallpaper?

If I select a trigger of receipt of a notification from an app then changes to wallpaper is greyed out. 

If I select what will the routine do as change wallpaper then the trigger of notification received is greyed out.

Other triggers allow wallpaper changes 

But notification and messages received cannot.