Validator.w3.org fails because of Let's Encrypt Cert?

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https://validator.w3.org/check?uri=https%3A%2F%2Ffiles.luo.ma%2Fview%2FMacSparky-Shortcuts-for-iOS-13-Shortcuts-Field-Guide.html&charset=(detect+automatically)&doctype=Inline&group=0 still says

500 Can't connect to files.luo.ma:443 (SSL connect attempt failed error:1414D172:SSL routines:tls12_check_peer_sigalg:wrong signature type)