FSD doesn't "work fine" driving directly into the sun. There are loads of YT videos that demonstrate this.

For which car? The older the car (hardware) version the worse it is. I've never had any front camera blinding issues with a 2022 car (HW3).

The thing to remember about cameras is what you see in an image/display is not what the camera sees. Processing the image reduces the dynamic range but FSD could work off of the raw sensor data.