When creating a custom gatelet, you cannot choose google.com for the URL
The reason is that google.com has a large amount of subdomains. Routing all google traffic for all domains through the gateway would greatly increase the processing needed with very little functionality benefit.
Create custom gatelets for any google subdomains that are needed to be monitored.
Previously, google subdomains could not be used in a Custom Gatelet either. Google subdomain support was added in 3.155 which was released January 12, 2023