Rotating the box, moving the seam, changing the seams settings all just move the problem. You can’t see in the photos, but there is an inner seam on a different corner as well that looks the same. The seam seems the same (lol) regardless of X or Y orientation. If I do “optimize wall order” it aligns the inner/outer seams and the deformation is even more dramatic, as you would expect.
The STL mesh seems fine, as do the animated paths in CURA
Its seems there is a delay for a the first few mm. Also seems like it maybe be overextruding a bit at the end of the wall, giving the “lump” + “cavity” effect seen in the photos.
I tried to do surface mode and it totally failed, spiral(vase) mode looks flawless though, both of which make sense given the symptoms.