Big banks like Natwest collect during your application. You’ll have supplied it, you just won’t remember.
Monzo got into hot water for not doing that so had to ask folks after the fact. My suspicion has long been that those accounts who were put on notice missed the email about it and so never supplied the info.
I suspect the reason why Starling have prompted you again, is because there’s been a change in how you use it (with moving things over again). Banks are supposed to stay on top of it and keep their records up to date, but every year is a bit much.
Besides the first time Monzo asked me, the only other time they’ve asked for it is when I applied for Flex, and that was more just them checking to see that stuff was still correct as it was all pre-populated. It was a bit outdated (inflation) so I updated then.