I am not sure when the phrase was coined but I’ve been hearing it a lot in the last 18 months as a pejorative. It came to the forefront with me in a Facebook discussion about wearing masks during the pandemic and someone I know posted that masks were useless and just virtue signaling. And this is the same guy who flies an American flag on the back of his pickup truck.
Doesn’t everybody signal virtue in some way? Isn’t it a normal societal thing to display tokens that indicate you are part of some group?