After upgrading my homelab to vSphere 7.0 Update 3, I noticed that my VMware Event Broker Appliance (VEBA) vSphere UI Plugin which is included as part of the VEBA Appliance was no longer functioning properly and would display no healthy upstream error message.
I initially thought this might be environmental, since I had just upgraded from lab from vSphere 7.0 Update 2d to 7.0 Update 3. I had reported the issue to our vSphere UI Engineers who built the VEBA UI plugin and while they were looking into the issue, we had another report from a VEBA user who also was hitting the same issue. Today, I got an update from Engineering and it looks like there was a regression in the Envoy service running in the VCSA which had caused this issue. This issue will be fixed in a future patch update for the VCSA, but in the mean time, VEBA users can apply the workaround outlined below.