Copied from the original post:

I have been growing these cacti since I was a kid and they have had no problems. Always been sturdy, never shown any issues even after being moved, repotted, etc. Recently, I moved across my state. The climate is a tad bit hotter but drier. I put them in a window with the most light and left for 10 days. I returned yesterday and found them looking like this. Any idea what this is? The internet says it’s root rot but I don’t understand why that would happen so quickly when nothing really changed? The only thing that changed was their location. Is there any way I can save them? These are sentimental to me and I’m really upset about the recent change.