A suit is formal, not sportswear or casual wear. I used to work in the clothing industry. When you don't wear a formal suit, your sleeves naturally lean forward 45 degrees, and you will feel tight when you wear them under your arms, because the elements of the suit itself are like this. Look, some of them are wearing suits and playing basketball or holding their arms high. It is usually worn on important occasions or dinner parties to correct the shape of a suit. So the traditional design concept of a suit is like this, hehe. If you think the cuffs of a suit are loose and you can move freely, then if you look at your back in the mirror, there will definitely be a wrinkle or a strip of cloth under your arm, which makes you feel uncomfortable. This has nothing to do with the size of the clothes. Your clothes fit you well.