Gradient Background With Random Color Lerp

What is the best way to get a gradient Background With Random Color Lerp in a Unity Project?

i am currently trying to make a gradient background With (random Colors) Color Lerp. i have made a script to control the color lerp with random colors for a material and it works superb but i am stuck for trying to do the same for a "GRADIENT". if you want more info for what i want here is the game i got this idea from and i think its possible for doing the same in unity but i am just not in the correct line. STACK GAME BY KETCHAPP : https://play.google.com/store/apps/details?id=com.ketchapp.stack&hl=en i want this background exactly the same which changes the colors slightly while moving. THANKS FOR YOUR HELP! appreciated :)