As part of setting up access to the vSphere+ / vSAN+ Cloud Service, a vCenter Cloud Gateway (VCGW) is deployed into your on-premises infrastructure and serves as a gateway between your vCenter Server(s) and the VMware Cloud Console.
If the VCGW has connectivity issues to the VMware Cloud Console for whatever reason, your infrastructure and workloads continue to run but you will not be able to perform any operations through the VMware Cloud Console until connectivity is restored.
UPDATE (06/21/23) - The period in which VMware declares a VCGW unreachable has been updated from 24hrs to 7 days. This means even if your VCGW loses connectivity, you will still be able to login to your on-premises vCenter Server and/or SDDC Manager without needing to go to emergency URL.
However, if you attempt to login into your on-premises vCenter Server(s) using the vSphere UI, you may be surprised to find the following error message.
While I will agree the user experience may not very intuitive, the hint is in the URL link below where it says "Still having connection problems?"