Cannot get type by full name despite this type exists and is loaded

Weird problem, I get System.TypeLoadException "Could not load type 'Color'":

using UnityEngine;

Type.GetType(typeof(Color).FullName, true);

Of course, I cannot just use typeof(Color), the code demonstrates that this type exists and is loaded and its name is correct.

typeof(Color).FullName == "UnityEngine.Color".

I also tried:

typeof(Color).Module.GetTypes().First(t => t.Name == "Color")

works fine, but

typeof(Color).Module.GetType("Color", true, false)

throws TypeLoadException. So I make a conclusion that it's not a "fully qualified name" problem but something else.

I also tried another types from UnityEngine assembly and from another 3rd-party assembly.

I checked Mono sources but related code is in C implementation and is quite difficult to comprehend quickly.