Hi, @Duchemin, Dominique
Thank you for posting in Microsoft Q&A forum.
It is expected that services will continue to run after certificate expiration, but it is not recommended to let certificates expire. While it is possible to continue running services, expired certificates can lead to security issues and other potential problems.
Regarding the difference in the number of certificates between Test and Production environments, this may be due to different certificate requirements for the two environments. Typically, a production environment may require additional certificates for redundancy or security reasons.
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