It has been hit miss for me, even before the update.
Wild speculation, previous versions of Safari might have had an issue with properly handling this, as websites that do support it have a specific syntax they need to code their websites to/for to allow. Or, a combination of above, add in possible new-ish web standards, and websites were not quite correct on how they code their pages.
Number of links out there re: how a site needs to do this, if wanting to dig deeper.