@Jay I just tried on another document and the text color is fine.
Actually, the bug seems to be that I can’t change the text colors from the colors menu ( in Notes panel).
When I select the text, the moment I open the color pallet menu the selection is gone, so my choice of color doesn’t affect anything.
So if I paste the text from a Word processor it inherits the text style and colors, and they can’t be changed or reset to the themes default.
Actually, an introduction of a button “Clear Formatting” probably is a god idea, as in this situation I can’t clear text font and size either.