I wonder how the new “Patch” tool of Rhino 9 handles this case with G2 curvature continuity, either with the top blue or the top green ellipse. Here is a test 3dm file from Rhino 7 where I built a patch with G1 tangency.
Patch test 1.3dm (558.4 KB)
I used the “Shaded 14” display mode for this test due to its highlight. It can be downloaded from this link: