Explanation:
Analyzing the situation exposed in the question above, it is correct to state that the manager was malicious in assuming the credits for his subordinate's extra work and acted in an unethical manner.
These situations can happen due to the fact that many employees are afraid to confront their manager for bad behavior due to their hierarchical position and the fear of being warned or losing their jobs, so these situations can be common in companies.
The ideal in this situation would be an assertive reaction, using an ethical and professional approach to know the manager's motivation to act in that way.
It is also valid for other employees to know that their work is being carried out, so that this type of manager behavior is minimized, as there may be a fear of being exposed by the team.
The relationship between manager and subordinate must be based on trust and mutual respect, so that the work is carried out efficiently and each one can do their best to achieve the team's goals.