Not sure what kind of editor you are pasting into, but if there is any conversion to RTF taking place, it may be done by the application's paste handling.
Looking at it more closely, I see that Google Docs itself doesn't itself place any RTF in the clipboard, only:
public-htmlpublic.utf8-plain-text
For clipboard inspection methods, see, for example:
Clipboard Viewer - Macro Library - Keyboard Maestro Discourse