I for one struggle with giving my characters Prejudices, so if anybody has any ideas post them here both for me and others!
Prejudice Ideas
What helped me find prejudices for my characters was thinking of their backstory. When you look into how your character was raised, you start to see the things they learned to be prejudiced against. Even if it isn't a valid prejudice, it can still help to show your character change as they realize that their view was wrong. Your character also doesn't need to have an extreme prejudice against something. Even if it's just a small feeling, it can help round out your character.
Here's a list of common prejudices; https://classroom.synonym.com/the-different-types-of-prejudice-12081909.html
https://www.verywellmind.com/what-is-prejudice-2795476
I hope these links helped!