Am I sinful if I publish someone's account on social media, and then he or someone else sends him prohibited material (such as裸体 photos, insults, curses, mockery, or links to songs) and he sees, hears, or reads it?

A person sins by guiding others to an account that is known for frequently publishing illicit content, such as pornographic accounts, because assisting in sin is forbidden, as Allah Almighty says: "And do not cooperate in sin and aggression." If the account occasionally publishes illicit content, it is safer to refrain from promoting it. However, if the account is not known for publishing illicit content, there is no sin upon the one who guides others to it.