iPad Air Books library search only finds a maximum of 10 items?

Been getting frustrated with searching my Books Library, where I have a collection with 170 pdf files saved and looking for all of the ones from 2021, and 2021 is part of the file names assigned and it finds only a max. of 10 items every time even with using another search parameter.

These are my blood test results and single pages for each item from the last 5 plus years and as an example in one years there could be a total of 50 pages for that year and yet searching only gives me ten each time!

I have tried many different search parameters and it always comes back with only ten results, and there are definitely more than 10 ……?

This gotta be a bug or something?