What UNIX are you using where that's a valid username? If Linux, what distribution?
Not disparaging it, just wondering. I agree that this is not how zsh should be behaving. Are other shells (e.g. bash, Korn, tcsh) behaving correctly?
PS1='\u >'Студент >
to write their native languages "Cyrillic", not "Cyryllic". Your English spelling and grammar is otherwise entirely acceptable.