Your date of birth may be correct with the University, but the date you're seeing could be translated from the Gregorian calendar to the Hijri calendar (sometimes understood to be the Islamic lunar calendar) + or - a day.
It is possible that this is happening because of a language or regional setting on the device or browser you are using.
If you want a quick sense check there are some useful converters online (example available at https://hijridates.com/en/date-converter.html).
If you are a new student, this will be checked when you complete your registration and your ID is checked anyway so please do not worry.
If you believe this is not the issue then please log an enquiry giving your date of birth and what our Online Registration service is showing.