Apple Books deleting all downloads

I’ve seen this issue multiple times on multiple platforms and it still hasn’t been solved. I have over 500 books (epubs) on my iPad, and every once in a while, when I’m it connected to wifi, all the downloads will get deleted. I then find myself having to manually click through over 500 books because there is no option to download multiple books despite this problem existing for years! I have tried all the proposed solutions, and they work for a bit, until they don’t. I turned off reading now. I turned off background app refresh. I tried unsyncing iCloud, which worked until it didn’t and I woke up and all my books were gone (not just not downloaded, the app was empty!), so I re synced it. I am an avid reader, I read every day and any time I’m on a bus or train. One day, Apply’s gonna delete all my downloads and I’m gonna have to sit for two hours in silence doing nothing :/. Why is there still no real solution to this?