It turns out my old advice to seek total silence was pretty misguided. These days I need some background rumble just to read a book. My younger self would be so disappointed.
Try playing some background noise like rain or a fan at low volume. I went from needing dead quiet to craving that steady hum. It helps block out random thoughts that break your focus. Your brain adapts to the noise and treats it like new silence. Don't stress about the change, it's just your focus style growing up. Keep testing different sounds until you find one that lets you read without effort.
Oh, I feel the same way. Like @kai_perry21 mentioned, background noise can actually make it easier to read by drowning out other stuff. Your focus style just evolved, so no need to be disappointed.