From wikipedia:

"Virtue signalling, spelled virtue signaling in the United States, is the conspicuous expression of moral values. The term was first used in signalling theory, to describe any behavior that could be used to signal virtue—especially piety among the religious In recent years, the term has become more commonly used as a pejorative by commentators to criticize what they regard as empty or superficial support of certain political views, and also used within groups to criticize their own members for valuing appearance over action."

"In the mid-2010s, many users on internet forums and social media gave 'virtue-signalling' a pejorative sense when they denounced such empty acts of public commitment to unexceptionable good causes such as changing Facebook profile pictures to support a cause, participating in the Ice Bucket Challenge, offering thoughts and prayers after a tragedy, celebrity speeches during award shows, and politicians pandering to constituents on ideological issues."