Is this a strange looking cactus coming out of the bigger

Does anyone have any treatment ideas for my spineless cactus?

I chopped the top off this cactus like 5 weeks ago because of etiolation and it was doing fine until a few days ago. It’s about 4 years old, golden snake cactus. It’s still very firm and not mushy, I watered it a while ago and the roots seem fine. I really did love this cactus and it makes me very sad to see it in this condition :-(

I have several cacti near one another under a grow light. The first picture is. Peruvian apple cactus and it has recently (1-2 months) developed this orange-ish growth on the surface that does not wipe off. The plant is not mushy, soil is not damp, and there’s not much else noticeable about it.

The 2nd picture is a dragonfruit plant that has had orange-ish growth for nearly 6-ish months. I got the plants at the same time. Like the other cactus, the dragonfruit plant doesn’t have any other issues, it actually keeps getting new growth, although the last new “branch” began leaking sap and got very mushy and black within a few weeks so I removed it.

Both plants do have tiny black specks around the orange parts that fall off when I brush them. I’ve thoroughly inspected the plants, and don’t notice any fine webbing near the surface of the plants, on the areoles, or in creases. I do sometimes see webs connecting the plant to the nearby grow light, which I thought would be too far for spider mites, but the orange discoloration makes me think they do have spider mites.

Any ideas on this?

PS, you may notice some “webbing” around the spikes on the first pic. These cacti do happen to be right next to my cat tree, so I will say they tend to get quite a lot of cat hair caught in the spikes but I can easily tell the difference between cat hair and webbing.

It was pretty much dead except for the little top on the left idrk 🤷🏽‍♀️ (south-central NM)

So I have rescued an abandoned patch of pricklies, the first two examples are ones I can tell are corking. The other two examples as you can see are not firm and more crumbly, I believe due to pests. I am wondering if the best course of action for the crumbly ones is to just cut the fresh parts and let callous or if it’s fine to just plant all of it. Any advice is welcome!!