When they are first applied, likely very little or no distortion/degradation is visible. Over time, however, the materials the lens protectors are made of can become scratched, dirty, or dull looking. This can have a deleterious effect on the quality of images. I've owned every top-tier flagship Galaxy phone since the S8 line, and I've personally never used camera lens protectors.
If they work for you, go for it! 🙂 Another reasonable alternative is to purchase a case that has a sliding/locking "door" for the camera module.
Scratches are inevitable. So giving a surface other than the screen and or camera lenses to be scratched is preferable