Darktable steals system default associations instead of user associations

On Manjaro Gnome I installed Darktable via pacman. All well.

However it stole the default associations of image files that are supported via gThumb. Worse, it changed the system default for image associations.

I understand I can add a line in $HOME/.config/mimeapps.list. This is the same as doing it via context menu on an image file, and changing the default application via Open With > Other Application.

However (apart from the fact I have to figure out for which file extension to do this), if I ever use the context menu on a PNG file > Open With > Other Application > Reset to system defaults, Darktable is again the default!
The system default before installing Darktable was gThumb and I find it incorrect that this is changed after installing an additional application.

I still want Darktable to be associated to image files. It should however not be the system default. How can I prevent this during Darktable install or solve this… also when Darktable gets updated?

Does anyone know how to solve this?

Here is an example of /usr/share/applications/mimeinfo.cache:


This is weird and happens to all image file types. Darktable is to edit images, not for viewing. It is also focused on editing raw images.

How to solve this?
Should people reinstall gthumb after installing Darktable?