Apple did actually make the limit a matter of their policy. Start date is September 1, technical enforcement comes 'later', but the requirement is going to be part of their policy. https://lists.cabforum.org/pipermail/public/2020-April/01494... Plus, it's not just Safari - it's the TLS stack in macOS/iOS etc. - Apple's KB article mentions nothing of Safari, but just like their enforcement of CT, it's basically OS-wide.