Kuro Neko

To further help others, this is before (new OEM), with the 7mm indentation un-pierced:



and after I've stuffed a 5mm hex T-handle through the indentation to release airbag spring:


As others have noted, it is upside down, at the bottom of the wheel, in the dark, and you need a light under any circumstances to see if the indentation has been pierced, and even then you need to be looking at the area directly, and know exactly what you are looking at.
Otherwise, it just looks like a small indentation, even if pierced...

Neko

Kuro Neko

Here's a late model wheel - the one with two airbag springs that need to be released, one on each side.
You can see the perspective and how small the indentation is: