Settled status app for non EU family member of dual citizen (Lounes?)

If I bring my mother over on a Settlement scheme family permit, to then apply for the Settlement scheme herself, it says she needs to provide

My EEA passport showing I was EEA before I became British
My British passport
Proof I exercised treaty rights and became a permanent resident before getting British citizenship
Showing I still exercise treaty rights

These are all easy except for the fact that at the time I applied for British citizenship, you could do.it directly without having a PR card first, and instead have your PR status assessed as part of that. So obviously by granting me British citizenship, I was assessed as indeed having PR.

I have no PR card though. Would I have to thus "re-prove" I exercised treaty rights for those 5 years prior to obtaining citizenship? There were so so so so many documents, since I was self sufficient, student worker, etc etc, and this was 10 years ago now, so I don't even know if I'd have all those documents still. I'd be very scared of bringing my mum over successfully only to have the SS application go sour over this.

My naturalision certificate is the proof I held PR since obviously I couldn't have become a citizen without being permanent but they seem to want proof of PR itself or the card which I don't have.

Any thoughts or experiences? Thanks!

​​​​​​​The caseworker guidance implies to me I need to reprove everything but on a page here I saw that you can prove either PR or that you were simply exercising rights at the time you naturalised? That would be easier as I was a student at that time and if all I need to prove is that specific status then great, but then what is the point of proving one specific treaty right exercise when they know I had PR by granting me citizenship anyway? Either way this would solve the above problem.