Fat malabsorption?

[Hi686]

After a bowel movement I see a very slight oil sheen( it is always clear ) on the surface of the toilet water.  I can't see it unless light is reflective off the water and I look at a sharp angle.  In other words it is there but barely noticeable.

Stool is not smell bad, and always just sinks , I am not losing weight either, I am consistently the same weight, colour is medium brown and is usually solid, I’ve had a recent clean colonoscopy and an OGD that showed, GERD and a hiatal hernia

I have read that the oily sheen is malabsorption.  Or is it normal to have a slight sheen on the water?  Again I can't see it unless I get down on my knees at the right angle. I also suffer with health anxiety