1. Create a new Toon Standard material and inspect it.
  2. Enable Detail texture, Specular, Matcap and/or Rim Lighting in a Toon Standard material by clicking on the checkbox. (E.g., Rim Lighting is enabled and set to a red color.)
  3. Right click the new Toon Shader material, Create → Material Variant, and inspect it.
  4. Notice the checkboxes for Detail texture, Specular, Matcap and Rim Lighting revert back to disabled state, but retain their other settings.
Generally, Material Variants remember their checkbox states between different shaders (i.e. Unity Standard, lilToon, Poiyomi). Mobile Toon Standard doesn't (yet).
Unity 2022.3.22f1
SDK 3.8.1-beta.3