Daughter 1st British Passport - HMPO asking for my Tax Records

Hi Admins,

I am a British National. My daughter was born in Pakistan and I applied for her British Passport from Pakistan in July 2021.
HMPO asked me to provide more documents 2-3 times via email and I did submitted them. Last week, they asked me to provide my NI Card, P60 and Payslips which I did provide as well.

Now today they called me and told me that as per HMRC record, my (father) date of birth is wrong, just a digit here and there from my actual date of birth. They agree that it must be a admin error as whoever entered my date of birth when I applied for my NI number 10 years ago, they must have hit a wrong digit.
HMPO is now asking me to correct it and then send them proof and then they will process my daughter's UK passport application. It is more than 4 months now since I applied.

Now HMRC will take their sweet time to correct my date of birth.
My Question here is if I have a British Passport and Naturalization Certificate with my correct date of birth, why HMPO is chasing HMRC to confirm my DOB?
My tax records are not required for my daughter British Passport, why HMPO is going that way?
Should I involve my MP?

Or should I just go with the flow and contact HMRC to correct my DOB and then provide it to HMPO.
Please advise. Thanks