Why is the Generative Fill going beyond the selection edges?

I am trying to generate a simple stethoscope. Why does the generative fill extend BEYOND the selection edges. None of the results are usable. Is this a known defect?

I cannot see any reason why that would be an accepted or wanted behavior to generate the image beyond the edges of the selection. Makes the whole thing useless IMO

Windows 10

Version 26.3.0