Hello there,
When you renew the CA certificate with the existing key pair, nothing important in the certificate is changed. The certificate will contain the same public and private keys. As the result, all previously issued certificates will chain up to a new CA cert without any changes. You just replace the old CRT file in AIA download locations.
Technically a root CA certificate cannot be renewed once expired. We can only generate a new CA certificate but when created using the existing key, it can be used to sign existing server certificates.
Root CA certificate renewal [https://social.technet.microsoft.com/wiki/contents/articles/2016.root-ca-certificate-renewal.aspx
Hope this resolves your Query !!
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