Hello,

For context of these plants, i'm in NorCal and both of the plants below get direct sunlight for at least 6+ hours.

The first photo is an indoor cactus, I think this is sunburn, but can anyone else advise if that's correct?

The second photo is an outdoor cactus that has grown wildly over a few years, but all of a sudden has produced these dark black spots. I hope it's not rot! Anyone have an idea?