To steelman this, it isn't abnormal for people to get a Bachelors in one thing and a masters or phd in another. Typically the school makes them do some pre-requisite courses for a foundation as part of the masters. I know someone for example with an english degree and a masters in data science, who had to take a couple additional statistics and programming courses, and another person with a math undergrad and a masters in electrical engineering that basically had to take circuits, E&M, and electronics (so a good chunk of the EE undergrad) before starting graduate courses.