If you’ve noticed your succulents changing color, don’t stress out. Sun stress is not a bad thing - and it’s something that’s actually encouraged in many types of succulents.
Have you ever seen a cactus plant that is of one color, maybe green, lower down and has a bright red top? Or a cactus that has a shape for what looks like the stalk, and then changes shape in its upper part? If so, you have seen what a grafted cactus looks like.