I’d like to think I’m taking care of it and taking it off nice but maybe I’m not. Your watch doesn’t have marks like that ? My wife has identical marks like mine. So I think it’s the charger. Not bothered by it just wondering if it’s not normal. I’ll work on removing it more carefully. Doesn’t bother me much. Most of those scratches aren’t visible unless under a good light source.
With the sport model, you have the composite backing, which can scratch, but what you have is likely very minor. I would just be cautious of the surfaces you set your watch down on, otherwise those micro scratches are not anything to be concerned with.
The stainless model has the ceramic backing, which is more scratch resistant, which I think Apple should use the ceramic backing for all their Apple Watch models, but of course they have separate hardware features to entice the consumer to upgrade to the most expensive model.