Warnings have been thrown on recent Chrome versions to console about this for a while now
EDIT: I'm an idiot, it didn't occur to me that Symantec didn't sign their own cert. But they don't, it's from DigiCert. Can anyone link to a site that uses Symantec certs?
Console throws up this warning about M70 though.
> The SSL certificate used to load resources from https://static.ctctcdn.com will be distrusted in M70. Once distrusted, users will be prevented from loading these resources. See https://g.co/chrome/symantecpkicerts for more information.
Says Symantec sold their cert business to DigiCert
So could it be a cert that was issued as Symantec and just now shows as DigiCert and would still give you the error?