This is a euphorbia ammak that I recently picked up. Don't know why I didn't notice these spots before. Would you say this is corking or something serious? It's not squishy or anything. Dry soil as well.

Nomoreplantspace yet you keep buying more...

It looks like corking. If its hard and dry to the touch, I would guess corking. I hope you have room (and the right zone) to plant it outside in your yard. It will be spectacular in a few years.

PS: We have a lot of wild and crazy cactus growers on this Forum.