There was the GIMP Coffee stain filter (though it looks like it is not included in Gimp 3). https://docs.gimp.org/2.10/en/script-fu-coffee-stain.html https://do

There was the GIMP Coffee stain filter (though it looks like it is not included in Gimp 3). https://docs.gimp.org/2.10/en/script-fu-coffee-stain.html https://docs.gimp.org/2.10/en/script-fu-coffee-stain.html