Using JCE 2.9.41 Pro, J! 4.3.4, PHP 8.0.30, ImageMagick selected.
Have set an image (jpg) as a watermark. I've chosen to place this is the top left corner with 1px margin. When uploading images and applying the watermark, the watermark picture is not placed in the top left corner with 1 px margin around. Horizontally it is in the right place, but vertically it is placed with appr. 45px margin from the top. Using a watermark image in .png fileformat produces the same results.
The displacement of the watermark appears related to the size of the image the watermark is applied on. When using an image roughly half the size of the image used to reproduce the above, the vertical displacement is +/- 22px instead of +/- 45 px. The margin to the left is still correctly applied to 1px.
Disabling PHP ImageMagick for image processing does not change the results.