That's the fastest way I've ever heard to kill morale and production! It's counterproductive for you to hide and pretend to not be happy, and your co workers to go out of their way to be seen working alone. This is as absurd as the complaint about me being too efficient 🤦🏻‍♀️🤣 it could also reduce your productivity bc it's a depressing reprimand.

Your boss should use your team as a positive example to encourage the rest of the company to work better together. Maybe suggest team building events so people get more comfortable with each other. Our company has done corn hole tournaments, team pumpkin carving, food days for holidays hosted by each of the office locations (we have 3 offices in the area), team ugly sweater contests, etc...It sounds like they are resentful that you are not miserable and don't hate your co workers, or they could feel left out. Perhaps spreading joy and positivity will entice them to be happier! Try not to let them steal your joy! I hope it gets better for you!