Just to document, we had a discussion about this as part of the SC’21 OOD User Group BoF. We think the issue is with the xfce config and not VMD specific based upon comparing screenshots of what we see at OSC with our VMD install and the screenshot already attached.
Path forward is to try to first get just a basic remote desktop working by following these instructions: Enable Interactive Desktop — Open OnDemand 2.0.13 documentation