If your research is based on yours previous papers, yes - it is ethical. But what is the ethical limit of self-citations? What percentage within Reference?
Armita Khalatbari Limaki, I agree with you. But should not be there an ethical limit? Because I have seen papers with very high percentage of selfcitations and it did not seems to be any editing issue.
Every scientist try to specialize in a particular niche. So, there is nothing wrong in citing their own work. We don't expect people to do a work, publish, and then move on to a next field or a domain.