NoVNC has never been a service in any version of TrueNAS. The services that were removed were largely replaced with apps, as described at the first link you quoted.
I understand that but the Apps are also broken now, because the bridge interface is buggy.
So, technically speaking, they have been removed because there is no easily working solution is available.
Also, if they removed the VNC support, why did not they remove the "Display" button from the VMs detailed sheet?
It is confusing, because one can think that it is there to show an image, but it just does not do anything.