Varanopids are basal to synapsids AND non-lepidosaur diapsids. We’ve known this for about a decade in the large reptile tree (LRT, 1837+ taxa, subset Fig. 1).
The Benoit et all 2021 study suffers from taxon exclusion
and from trying to ‘Pull a Larry Martin’ by examining only the maxillary canals of several cherry-picked taxa using µCT scans without a valid phylogenetic context (Fig. 1). These authors had no idea that lepidosaur diapsids are NOT related to archosauromorph diapsids.
Benoit J, Ford DP, Miyamae JA and Ruf I 2021. Can maxillary canal morphology inform varanopod phylogenetic affinities? Acta Palaeontologica Polonica 66 (x): xxx?xxx, 2021. https://doi.org/10.4202/app.00816.2020