@chrillek You are correct. Removal of image tags is not mentioned in the documentation, though I did find reference to the behavior here.
I’ve created an issue to update the documentation.
Please note that all tags are removed: EXIF, IPTC, XMP, etc. If you use something like exiftool to read the tags after image processing, it might look like some tags are retained, but the data displayed is extracted from the file and image properties–none of it is EXIF data.
Also note that the original file is untouched.