A light’s rgb_color attribute exists only when the light is on. When the light is off the attribute doesn’t exist so any template that attempts to access the non-existent attribute will not succeed.
If you are using Google Translate, you should know that this is almost meaningless in English. I assume you are trying to say that the light is on but Home Assistant still reports an error.
It is saying that the name “color_base” is unacceptable and suggests “solor_base” as a replacement. The important point is that the first letter of “color_base” is invalid and so it offers “solor_base”.
I examined the hex codes for the text you posted. Each letter has a corresponding hexadecimal number equivalent (hex code). For example, the hex code for the letter c is 63.
I don’t know what kind of keyboard or text editor you are using but somehow you entered what is known as a double-byte character. This kind of character is unacceptable for use when defining an entity’s name.
Here is the error message when I test it with the c double-byte character:
You are absolutely right, it turned out to be the Russian letter S, in spelling it is completely similar to the letter C. However, you should know this yourself, you have a very Ukrainian name))