Just to estimate the magnitude of impact on end-users with older MacOS / iOS versions when DST Root X3 expires (and for whom the Android workaround won't help), is there a list somewhere of major websites that are using Let's Encrypt certificates? Like Wikipedia etc.
If significant portions of the Internet become unusable for those clients, they will be less likely to blame (smaller) individual LE certified websites. Or at least those smaller site owners can tell them "please test Wikipedia as well" to convince customers the issue is on their side.
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