Hi, @Jeffrey Tucker
Thank you for posting in Microsoft Q&A forum.
The site system certs should get renewed automatically.
You might need to open a support case for this.
Here is the link of CSS support:
https://support.microsoft.com/en-us/hub/4343728/support-for-business
For the reference:
https://www.reddit.com/r/SCCM/comments/iyaykl/sms_issuing_certificate_is_not_being_renewed/
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