Kirby tag generates extra unnecessary files in media folder

Not sure if this expected behaviour or not and can be ignored but i noticed today that when using the Kirby image tag eg `(image: somefile.jpg)` in a text area field, i can see a bunch of job files getting generated in the media folder for various different image sizes and crops

Whilst the image tag works and outputs the image as expected, those jobs never get completed, i guess because those images never get requested. This means those jobs files just end up hang around forever. Here a screen shot of the folder

Is there are a reason for this or is a minor bug or something?