HTTP 500 failure is seen on the HCX Transport Analytics tab. Everything in HCX will continue to function (Site Pairs, Service Meshes, Appliance Tunnels, Migration, etc.) but you see this error in your OnPrem HCX plug-in.
You see this error on the HCX Transport Analytics tab when accessing the OnPrem HCX Plugin through vCenter (VC). Similar error will look like - "Http failure response for https://vcenter-name/ui/hcx/hcx-ui/rest/hybridity/api/ 500 OK"
VMware HCX
Because the issue appears to be related to the OnPrem HCX Plug-in, the recommendation is to remove the plug-in and re-add it to the OnPrem vCenter.
To remove the plug-in from the OnPrem VC: