So, I have a similar problem with a virtual cam (but not with another by the same publisher).
On Mac, iGlasses works great. The iGlasses zoom works fine. In Ecamm, same publisher, the 16:9 GTM version is actually a 4:3 letterboxed which means that it's double cropped. It's first cropped into a 4:3 and then by selecting 16:9, top and bottom are cropped. Very bizarre!!!!
I have this same issue using a Canon HF r800 camera going through a Mirabox USB 3.0 capture card. For several months this worked great, but in the last week or two the video looks elongated. No settings in GotoWebinar affect it.
Previously, when I started my video it would appear elongated for 2 -3 seconds and then snap into the correct aspect ratio. Now it never corrects itself. Video looks fine in Windows Camera, Zoom, and Teams. In Zoom I have to select the "HD Option" for it work, but then it works fine. Only GoToWebinar has this problem.