Text in associated label:
Works in all scenarios.
Image with alt text in associated label:
Works in all scenarios.
CSS background-image with hidden text:
Does not work in high-contrast mode (background image disappears).
CSS background-image with aria-required:
Does not work in high-contrast mode (background image disappears).
Asterisk w/ aria-hidden and aria-required:
Works in all scenarios (asterisk is not red in high-contrast mode).