HMRC asking for £800 from when I was a child

I’ve been working the last few years, however going back to review my tax code as my employer had incorrectly filled my Tax code meaning I was overpaying tax I opened my NIN contributions and it appears HMRC are requesting I send them over £800 by April 5th 2025 as a “Voluntary contribution” to cover a debt from when I wasn’t working because I was a child. I’m very confused as to why they’re asking for nearly £1000 off me and where they’ve gotten this from. The date on their form states from 2017/2018. I was unemployed and in College at this time. I’d do not graduate until 2019.

Hi Silence,
This will be a voluntary payment that you can choose to pay, for a year where you have a shortfall in your National Insurance records.
Anything shown as ‘voluntary’ is not a bill and it is your choice whether you choose to pay the voluntary National Insurance contribution or not. 
Thank you.