display:contents

The element itself does not generate any boxes, but its children and pseudo-elements still generate boxes as normal. For the purposes of box generation and layout, the element must be treated as if it had been replaced with its children and pseudo-elements in the document tree.

https://drafts.csswg.org/css-display/#valdef-display-contents

"being rendered"

An element is being rendered if it has any associated CSS layout boxes, SVG layout boxes, or some equivalent in other styling languages.

https://html.spec.whatwg.org/multipage/rendering.html#being-rendered

So an element that is display:contents is not "being rendered". Check the uses of "being rendered" if that makes sense.

Related: w3c/csswg-drafts#540