Max Mara weekend short sleeves sweater size L / fits a S/M

Beautiful sweater - pls read measurements for a better fit indication: I’d say it fits a S/M but the tag indicates L Armpit to armpit 17 1/2” Sleeves from shoulder 11” Waist laying flat 32” Inseam almost 23” Hand wash cold 100% cotton Color: olive green 🫒 Bought in a local boutique