Hi saving-chest,
The colors come from the Vertex Tag.
https://help.maxon.net/c4d/2023/en-us/Default.htm#html/TVERTEXCOLOR.html
I do not have your file here, so I can't tell what is happening on your side.
How did you create the file, where did you get it from, and what does the color have as its origin?
Cheers