Your hair looks in really excellent condition and it won't have lost that, don't worry, it is just going through a phase for reasons we're not quite sure of but I think the tips people have given you could well be the reason. I haven't really done homemade DTs, so I can't really help there, sorry - I have just added bits of oil to shop bought conditioners. I agree you should keep things really simple.

It sounds like the dye was chosen/applied in a careful way so I don't think that is it, and really without a damaging chemical or heat incident your hair will not have dried out irreparably or been is just acting up. I think low poo and avoiding major protein/heavy treatments for a bit might do it. But I don't like the look of those mousse ingredients, seems like a lot of potentially drying things and not much moisture.
UK based wavy

Mostly waves, but curls and straight bits too!
Fine to medium, high porosity, medium density, very low elasticity
Highlights damage (growing it out), seems to like protein and need lots of moisture.

Cleanse - CJDF, trying out low poos ; Co wash- Uk chemist brands, Urtekram Rose or Aloe, Hairveda Amala Cream Rinse; RO - varies, Tigi Moisture Maniac, Desert Essence Coconut ; Leave in - Keracare natural textures; Sealant - argan oil
Trying out new things, still looking.