Step-by-step explanation:
In this situation, you can perceive an unethical attitude from your manager, because he has taken credit for the extra work done by you before the president of the company.
So in this situation, it is ideal to have a dialogue between you and your manager in order to clarify the situation that has occurred. Because many managers can act dishonestly with their subordinates because many feel cornered to question the manager's attitudes for fear of reprisals.
It is also ideal that there is support from the rest of the team for a collaborator who is truly unfair because of a situation of abuse of authority, because this way bad behaviors are inhibited and an organizational climate is created, focused on transparency and ethical behaviors.