What books did you read bc you watched a movie it was based on only to find out the movie was a bad adaption?

Hello all I just had a funny question that came to me in the shower bc of my experience with Lotr. So I am viewing the movies for the first time now having finished reading the books. And I am getting quite annoyed at everything PJ changed from the source material (I made posts on the two I’ve seen so far if you are interested) which got me thinking.

What if I had seen the Lotr movies first, then read the books. What would my opinion on the movies be after reading the books now knowing how much was changed?

Then I remembered this actually happened to me twice. With both Percy Jackson and The Maze Runner I saw the movie first and liked them so I decided to read the book. While reading the books I was intrigued by how different the two were where events I expected to happen bc of what I had seen in the film just didn’t happen at all in the story or where changed.

After reading at some point I watched the movie again and really soured on the movie that I liked so much initially bc of how different it was from the source material that it encouraged me to read.

Has this ever happened to you guys and so what was the book?