Windows Popup from Avast Prem. Secur. for non-secured site

On our 3 laptops Windows 10,11 since 4 days, we have the following pop-up each time we start an MS-Office tool (i.e. Word, Excel, Outlook);

French Pop-Up

“La connexion à ce site n’est pas sécurisée
Avast a bloqué l’accès au site https://uci.edog.cdn.office.net/ car l’un des émetteurs du certificat a expiré
…/…
Certificat cdn.cdi.officeapps.live.com
Emetteur Microsoft Azure ECC TLS Issuing CA 01
Détecté par Agent Web”

What does it mean please?
Thanks a lot

Continue to monitor the other topic you posted in - https://forum.avast.com/index.php?topic=327907.msg1720276#msg1720276 - it tells you why in that topic.
Keeping all together, rather than create another me too topic.