The role of Scrum Masters is more the role of coaching a person who is between the project and the client. The Scrum Master does not manage the team that does the work - instead, it supports the product owner, trains the team and ensures that the Scrum processes are followed. The Scrum Master is responsible for the Scrum process, its proper implementation and maximization of its benefits.
Product owners have a huge responsibility for the project. They are responsible for the list of requirements for the functionality of the product that must meet the requirements of the business. During any project, as customers become more aware of the product or changes in the market, the product often needs to be changed to meet new requirements. The owner of the product must adjust and change the priorities of the list of requirements for the functionality of the product in order to comply with these changes and further effectively manage the project. This is a responsible task that only product owners can handle.
In this case, the Scrum Master should help to look at the project from all sides and advise the product owner about user experience about problems with product functionality, about feedback from users about the need to rebuild product development in accordance with changes outside the business.