Neat little tool, playing around with it.

Not quite sure what the difference in a "icon tag" and a "styling icon" is, but it looks like once a styling icon has been set (to a third-party logo), the icon can never be changed again back to a default shape.

This one has been set back to Shape: Firewall, but continues to show the OPNsense logo forever, and it cannot be changed without destroying the node.