Books app on iPhone causes battery drain, overheating, and reloads frequently

I’ve been downloading epubs into my books app for a long time but recently the app has started taking up a lot of battery power and making my phone really hot. the app also reloads to the home page before reopening the book every single time i leave even if it was only to check another app briefly and i didn’t close books. this has never happened before last week and i’m curious what might be the cause and if i can fix it