The advantage is to keep warm, but the disadvantage is that it does not absorb sweat.
On the whole, velvet shirts are ok, only suitable for months when it is cold in winter and you don't sweat. At other times, it is not appropriate to sweat a little. Its advantage is to keep warm. The disadvantage is also obvious, and it does not absorb sweat at all. As long as you sweat a little, your back will get cold, and it will be uncomfortable to wear if you don't absorb it for a long time.