When a newer version of VTK is provided OpenXR is built with instead of OpenVR.
OpenXR is an open standard which VR vendors support/provide implementations of. This allows usage of VR platforms in a more native way. Ex: OpenVR requires steamVR to run on top of Oculus. OpenXR just requires Oculus. See more details: https://gitlab.kitware.com/iMSTK/iMSTK/-/issues/386