Please see below link for Impact after the expiry and before the expiry period.
I believe there will be no impacts for Global Protect customers.
It may be necessary to log out and back from the VPN for the certificate to be changed.
What's not interesting is letting it expire, because customers will no longer have access to Global Protect.
Click Accept as Solution to acknowledge that the answer to your question has been provided.
The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!
These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!
The LIVEcommunity thanks you for your participation!