I make a new addon: “Mark linked collections” this addon help to see in the outliner your linked collection by mark them, so you can know which collection is linked (from other file or from other scene).
I write this add-on after I worked on a project with a lot of scenes, and I have some collections that were linked from one scene to other scenes (like props or background collections). My problem was that I was not able to know which collection is linked, and sometimes I add animation or edit the objects in the linked collections and after some time I see that it was a linked collection, and it ruin my other scene with unwanted animations…
So now with this add-on you can know which collection are linked to another scene just by look at the outliner and avoid of ruin your projects by mistake.
If you have any question about it or suggestion I will like to hear
Get it from the blender market: