Hi,
When using the Highcontrast option, GNOME-Shell is not using toggle-on-hc.svg or toggle-off-hc.svg and instead uses toggle-on-dark.svg or toggle-off-hc.svg
toggle-on-hc.svg
toggle-off-hc.svg
toggle-on-dark.svg
Screencast_from_10-06-2021_09_51_10_PM