Certificat let's encrypt untrust

Hello everyone ,

I recently updated my let's encrypt certificate.
This is considered unreliable by the sophos.
While it is valid.
I use it in WAF rules and it works well.
No message from different browsers.

As the certificate is considered invalid the cannot be used for access to the administration console

Do you have any idea why my certificate is deemed unreliable?

Thanks



Added TAGs
[edited by: emmosophos at 6:39 PM (GMT -7) on 6 Oct 2021]