When i have built the MSIX file from VS2022 and click on it to install the application, in the top right hand corner the icon has a background sitting around my icon.

Also when I create a shortcut on the desktop, it also has a tile background.

For example, in the screenshot below, the green shape represents my icon which has a transparent background, but it is within a blue square.

MSIX Installer

Then for the shortcut, you can see in the screenshot below that it has a blue tile around the icon. (the black colour is just my desktop background)

Desktop Shortcut

I know that this is controlled by the Windows 11 theme, because if I change my theme, the tile colours change.

I need the MSIX installer to just show my icon with no background like many other apps, see the example below:

Advanced installer installer example

Advanced installer shortcut example