https://cabforum.org/2025/04/11/ballot-sc081v3-introduce-sch...
https://cabforum.org/2025/04/11/ballot-sc081v3-introduce-sch...
You cannot issue a publicly trusted TLS certificate with an empty expiry, or an expiry date more than 200 days away (as of March). If you want to talk about private CA, then the certs can follow all sorts of rules.. they don't even have to be about TLS.. they can be for SSH at that point.
Expiry is optional. Is that a good idea? No.
Expiry exists only to kill a certificate, intentionally, in a timely manner. That forces the consumer to handle their business before certificate compromise, because revocation and compromise each invoke a higher effort to mitigate to the issuer.
You can create your own without the use of cloudflare.. you can set it to a 100y expiry if you feel like it.