Why does the interview require a full-body photo?

You may need to leave your photo. If junior recruiters think you have passed the exam, they will report it to senior decision makers and consider whether to continue interviewing you or eliminate or hire you. At this time, it will be a good reference if you have your photo. After all, people's appearance is very important now, so it's better to apply for etiquette. It is for this reason that people can't want to be fat or have spots on their faces.

So it is very likely that the company you are interviewing for has a high demand for appearance, or it is for higher-level leaders to make decisions:)