QGIS » QGIS Application

I have two polygon layers, both with snapping on and both with 'avoid intersections' ticked.

I expect that when I reshape a polygon in one layer, overlapping a polygon in the other layer, that the final generated line will be flush with the existing polygon, i.e. with the same behavious as when digitising a polygon and it overlaps another in the same layer. However, the reshaped part is accepted regardless.

I also expect reshape to result in a flush original border when my reshape overlaps a polygon in the same layer. However in this case it cookie cuts the overlapped polygon.

I would think all these workflows should behave the same as if digitising a new polygon, or is that assumption incorrect?