EU settlement reference number for citizenship application

[WithDBr]

Not sure if anyone has come across this before:
EU citizen, I have the settlement status granted since Brexit. Now, the application asks for: Was your indefinitely leave to enter or remain granted under the EU settlement scheme? to which the answer is obviously "Yes"
Next question is for the reference number, which one can get online.

However, this reference number expires after 90 days. However the citizenship application can take up to 6 months to be processed. what if the Home office only processes my application in the 4th month, and the reference number has expired?

another question in the form states:
"Have you made any previous UK immigration applications in the UK or abroad?"
Does this count the application of permanent residency (Prior to the EU settlement scheme being in place or brexit happening)? if so, I am a bit stuck for the date of application or the reference number, as it was a paper submission and only thing i got back was the residency document itself.

If anyone has any guidance, it would be much appreciated,

Thank you.

[contorted_svy]

It is asking for the URN of the application (16 digits if I remember correctly) which appears on the letter you should have received with confirmation of your status, not the online share code.
It does count as an immigration application so you do need to answer Yes to that question. If you don't remember/can't retrieve the details, you can either write what you remember at the best of your recollection (details are only "if known and it won't affect your statutory requirements) or request a SAR with UKVI and see if you can retrieve anything (it could be a relatively old record who UKVI may not have kept).

[WithDBr]

that is very helpful, thank you. And it does clarify the "Have you made any previous UK immigration applications in the UK or abroad?" question.

however, in terms of the : Was your indefinitely leave to enter or remain granted under the EU settlement scheme? reference number - will i be using the URN number there as well?

[contorted_svy]

If you applied for permanent residence before Brexit, then no, as your application was not done under the EUSS.