Just because "degrees" was dropped, doesn't mean that kelvin becomes plural. I know that it is more correct to say "200 kelvin" now.
Yes, language evolves based on misuse. When misuse becomes common enough, it becomes correct. This means that "kelvins" is not incorrect. Using just "kelvin" is still the correct form in scientific fields, though.
https://www.oxfordlearnersdictionari...english/kelvinOriginally Posted by Oxford Dictionary