Dell XPS 13 screen becomes fuzzy after windows 10 update

There are 8 XPS 13 models. Which specific XPS 13? How long have you had this laptop? How long were you using it before the issue started?

Run the LCD BIST (Built In Self Test)
* Power off the Dell laptop
* Connect the AC adapter (charger) to the laptop
* Disconnect all peripherals (mouse, keyboard, monitor, USB key, etc.) from the laptop
* Press and hold the D key and then press the power button. The LCD BIST mode should appear
* Continue to hold the D key, until you see color bars on the LCD. The LCD will display multiple color bars and change colors on the entire screen to red, green and blue
* Press the Esc key to Exit

If the issue is not seen when running the LCD BIST, then the fault is not with the LCD panel or its cabling. The fault must be with the GPU, the GPU driver, or the operating system itself. You should reinstall all of the Chipset drivers, restarting after each one. Then reinstall the GPU driver, restarting when done. Then retest.