https://www.w3.org/TR/mediaqueries-5/#inverted - The media queries level 5 spec is pretty clear that the inverted-colors media query should only match when all pixels have been inverted (as is the case with macOS' Classic Invert setting) and NOT when the UA has done some smart invert (as is the case with macOS' "Invert colours" setting when "Classic Invert" isn't also checked).
Safari (at least on macOS) does the opposite of this. When "Invert colours" is checked, but "Classic Invert" is not, the media query matches. But when "Classic Invert" is then toggled the media query no longer matches.
It would be good if Safari was updated to match the specs behaviour, cause otherwise this media query is effectively useless to developers.