The correct answer to this open question is the following.
Some people have negative attitudes and use negative strokes that hurt others. Is giving negative strokes unethical behavior?
Yes, we can say so, including that these people are rude and lack of education.
Why is it unethical? Because in order to live in harmony, people have to respect and tolerate other people, knowing that not all believe, think, and act as I do. But if we want to live in peace and harmony, great moral values such as respect, tolerance, communication, and compassion, have to be part of our daily lives. Without them, then we would be acting like "animals" trying to survive like in the law of the jungle.