Samsung S22 Ultra. Probably battery life, specifically that 15% means "you have 5 minutes left". And how long it takes to open the camera app and take a photo.
OS is okay, performance outside of the camera issue is okay, size, camera quality, screen, s-pen... I could have changed it this year and chose to skip. I might change it next year or even try to make it to 2026. New battery might be needed for that.