I also tried an experiment with your image where I used a vertical pixel offset (295 pixels downward) to make the cement wall wrap around the bottom of the image and appear at the top of the image. This offset aligned the original top of the wall with the top edge of the image boundary, so that the image appears to have the cement wall hanging from the top of the image. I ran Sharpen AI on the image, default Sharpen values, and no artifact appeared along the top edge of the offset image. Upon applying a negative offset to reposition the image to its original appearance, the image is artifact-free, without having to mirror the broad, uniform sky area pixels to achieve the same output.
So, it would appear that the top edge of the image may be prone to artifact if it contains areas of broad, uniform tone/color, whereas it will be okay if it contains detail.
A kludge to experiment with and verify might be that if you are getting artifacts in images with broad, uniform areas of color or tone at the top of your images, offset the image so that detailed areas of the image are positioned along the top of the image and then run SharpenAI, then apply negative offset to return the image to its original position.
Kirk