Le Chateau Knit top with 3/4 length sleeves

Lovely muted green top with gold button details. Beautiful top, great for going to the office in the summer. I would call if a light weight sweater or a knit long-sleeved tee? A bit hard to describe. Says small but would fit M too just a bit more snugly. Some light piling from wear but also some inconsistencies in fabric from nature of fabric and weave, not from wear. (Example in last photo). Somewhat sheer. Approximate Lay-flat Measurements: Across chest: 16.5” Waist: 16” Length: 29”