Exercise in a fitness way is easy to sweat. It is very bad for the skin to wear a coat at this time, so it is really understandable for a man to take off his coat at this time and should not be blamed.
People who scold you for your lack of quality may not understand these truths, be too narrow-minded and always impose their own standards on others. Don't worry about him, he can't do anything about you.
It's not uncivilized for men not to wear shirts in the gym, so you can still do this when you exercise in the future! Don't care about others.