In VDI Mode, Teams should block making calls audio/video when MSTeamsRedirSupport is set to 0
If the endpoint Citrix Receiver/WorkspaceApp insalled version is not supporting Teams Virtual Channel (1907 or higher) then Teams should not allow users to makes audio/video calls. This is consuming CPU on the server-side and calls performance are bad anyway.
There is already something like that in Teams but limited to endpoints with Workspace App when the virtual channel exists but doesn't work "Citrix HDX Not Connected" (see screenshot).
John Kelly commented
100% agree. Spend hours with Citrix/MS on registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Teams\DisableFallback.
Only to find that this only works if you HAVE a Citrix Workspace version which actually SUPPORTS optimisation. Which means it is useful 1% of the time. Needs to disable fallback when a client connects with a CWA or receiver version which CANNOT ever optimise. <1907