Diagnostics for VMware Cloud Foundation is a centralized platform that monitors the overall operational status of the VMware Cloud Foundation software stack.
It is a self-service platform that helps you analyze and troubleshoot the components of VMware Cloud Foundation, including vCenter, ESXi, vSAN, capabilities such as vSphere vMotion, snapshots, VM provisioning, and other issues including security advisories and certificates. As an Infrastructure admin, you can monitor the operational state of your environment using diagnostics findings and custom pages. Diagnostics validates if your environment is up-to-date with the important VMware Security Advisories" -> "Diagnostics validates if your environment is impacted by important VMware Security Advisories.
For more information please visit - What is Diagnostics for VMware Cloud Foundation
You can activate the diagnostics capabilities for your VMware Cloud Foundation environments by configuring integrations to them, and by installing and configuring VMware Aria Operations for Logs.
Please see the documentation to configure integration of Diagnostics for VMware Cloud Foundation and VMware Aria Operations for Logs: Setting up Diagnostics for VMware Cloud Foundation