Hi. I just moved into a place in SoCal (I'm from the east coast so I'm completely unfamiliar with any of this plantlife) and the place I've moved into has these really interesting cactus, but I'm worried there's something wrong with them. They've been turning yellowish, as pictured, and they've been losing parts (leaves?), as well as growing white tufts in areas. I cant find any causes for this online or if it's normal. I really want to be able to take care of them, so if anyone has any advice I'd be really grateful. These are pictures of two different plants, there's also one more in our front yard that looks similar.
Thank you so much!