What is included in the end of service gratuity?

Good day,

My end of service date was indicated.

I was told that my end-of-service gratuity will be compared vs. annual bonus payments during my employment and since my start of service to see from which I have received the most benefit.

How legitimate is this in accordance with the UAE Law?

Any bonus payments over the years and the end-of-service gratuity is free-standing, correct?

Thanks