I noticed that some of my clients who has itching scalp after applying hair dye has very sensitive skin. Strand test works fine at first but when the whole hair get covered issues land.

Also see my content on similar issues. https://hairshepherd.com/scalp-itch-after-color-hair/

mine definitely does, and the salon I go to uses all 'organic' products. I think it's just the price you pay.