When Guest Users are disabled from the backend to use the Color Detection feature, they cannot use that feature to the images they upload onto their products.
Login to Backend
Navigate to Stores -> Configuration.
You will be directed to Stores -> Configuration page. Go to Brush Your Ideas and in that, click on Product Designer Settings. Scroll down to Image Color Conversion.
Go to Enable Image Color Convert For Guest User and select “No” option.
This will restrict the Guest Users to use color detection.