Sometimes you need to bake all lighting into the diffuse color of the texture.
in the new release 2021 (from version 07) you can find this command on Textures > Light Baking Tool > Light and Reflections
Thx @sprayer for sharing this video
Open shader ball for example, fill layer with any reflective Smart Material, bake your reflection and it creates reflection layer in texture.
* @Silas Merlinadvice: if bake is too dark try modifying setting intensity.
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