I provided 3 months bank statements and a bank certificate including photocopying my savings bank account which from 2022 onwards (as it doesn't have many transactions) which showed my balance not dipping below the required amount. I was shocked when the officer said they wanted photocopies of every page in the book dating back to 2019!
Last year I didn't encounter this issue. Seems like extra tea money for the photocopying shop behind perhaps?
On another note, they don't accept children's ID as ID, you need to submit their birth certificates. Perhaps because the passport doesn't state the parents is the reason.