Transparency about your personal data procesisng is part of the first data protection principle.
It goes along with lawfulness and fairness.
You might consider these to be your ethical responsibilities.
Sometimes there can be a bit of a disconnect between what the regulation says you should be doing and what is ethically acceptable (just because you can do a thing doesn’t mean to say you should do it). Happily the GDPR contains this first data protection principle which combines both regulation and a little bit of ethics.
It simply says this,
“Personal data shall be processed lawfully, fairly and in a transparent manner in relation to the data subject.”
Yet there is SO much activity involved in delivering lawfulness, fairness and transparency.