Is the money earned by an emergency room doctor, who is in his final year of medical school and has informed his colleagues that he is in his internship year, unlawful (haram)?

If the applicant is qualified for the work and performs it as required, then his wage is not unlawful (haram (definition)). However, he incurs sin by lying to his employer and by violating regulations. If he makes a mistake in his work, he is treated like someone who practices medicine without being a physician; he is held accountable for his mistakes, whether accidental or intentional, based on the Prophet's (peace be upon him) saying: "Whoever practices medicine, while not known to be a physician, is liable."