If a person is mentally ill and harms people with his character, is he sinful?

A Muslim must strive to improve their character to prevent their harm from reaching other Muslims, and they must exert effort in this regard. If they are unable due to a psychological illness, then "Allah does not burden a soul beyond its capacity." However, as long as the will remains and it is possible to acquire good manners, and for Muslims to be safe from their harm, then the obligation is not lifted from them, as long as they are an adult of sound mind.