One minor nitpick: in social media the criticism generally applies mostly to mere statements, especially statements of support or outrage over any given emotionally loaded issue.
Attending a protest or donating to charity is relatively risky and expensive in comparison to just feigning outrage, retweeting slogans or changing your avatar.
Yeah virtue signaling is mostly a Facebook/Twitter thing.
YouTube too. Just pick any Sargon of Akkad video at random, it's almost guaranteed to be about either "virtue signalling", "moral busybodies" (i.e. the people mostly engaging in virtue signalling) or "cultural Marxism".
https://en.wikipedia.org/wiki/Virtue_signalling
The short version is, it's when someone acts in a "moral" fashion not because they truly believe it, but because they want others to see them as virtuous. Imagine someone attending a protest purely so that their friends can see them protesting, or donating to charity just so they can tell everyone that they donated.