Subdivision modifier curving edge (2.80)
The edge in the center of the image is getting curved by the subsurf modifier, causing all kinds of chaos. Left alone, it causes a weird shading artifact. But when adding a loop cut as a holding edge, it tosses the new vertex out along that curve (in the same plane), causing the geometry to hang over the corner:
No amount of jiggling the vertices or recalculating normals seems to fix it. Setting the edge's Crease strength to 1 keeps it straight but causes more shading artifacts at the two vertices. As far as I can see, my geometry in that area is identical to yours.
Is there some way to fix that edge?