I originally reported this as a bug a while ago
But I come at it from a new angle this time.
That input pins are always on the canvas and cannot be included in regions.
If you accidentally capture an input pin in a region (via surround tool, copy and paste or ctrl drag) then they no longer work and give an unspecifc warning ‘a pin with this name is not allowed in this patch’
As input pins always describe an input from the canvas context there is no reason for them to ever be in a region (Unless this is part of upcoming functionality?)