vMix Call needs at least 1 virtual background option and that could be as simple as a virtual green screen. Then, the event producer can replace that with whatever background the producer wants. I'm sure the makers of vMix have reasons for not having a virtual background for vMix Call to the level of Zoom or Teams. But, I have to imagine that it could be possible to have 1 standard virtual option and that would be a virtual green screen. Half of the guests I work with on a weekly basis are dismayed by not having the virtual background option. I know there are workarounds like xSplit vCam, but you can't expect a guest to install 3rd party software for a vMix event.