My Christmas cactus is turning purple. Why?
The cactus sits where it gets fairly bright, indirect light.
Purplish hue on leaves is often associated with potassium deficiency. https://www.gardeningknowhow.com/plant-problems/environmental/leaves-turning-reddish-purple.htm
The leaves on your plants look kind of soft and desiccated also, which indicate some cultural problems also, beginning with too little water, or too frequent drying out. This article has some tips on care of Christmas cactus: