At present the universal, public, background-assumption is of a mechanical-random world; and therefore 'the question' is simply about our-selves, how we feel - our happiness, misery etc. For all mainstream discourse the bottom line is psychology: my psychology; especially my feelings. There is nothing deeper.
(What else could it be, in such a reality?)
Other people are - we found, difficult or impossible to deny; they have a big impact on happiness, misery etc; therefore, some account must be taken of them... But 'other people' are ultimately defined in terms of their impact on how-we-personally-feel.
Therefore modern people aspire to social arrangements that gratify them-selves, that which make them feel good, not bad.
Modern people are concerned with 'virtue' insofar as they believe virtue affects their own psychological condition (by assumption, virtue cannot affect ultimate reality, which is indifferent).
Virtue works (or fails) by the attitudes that others have to us - as individuals, and how that makes us feel.
Thus (from these near-universal assumptions) all virtue, all possible virtue, the definition of virtue just-is virtue-signalling.
Virtue is a social communication that (we believe) will encourage other-people to treat us in such ways that we are more happy and suffer less.
There is nothing else that virtue could be, even in theory.
So: to accuse a typical modern person of virtue signalling is an empty insult. A modern person cannot conceptualise anything else that virtue could possibly be than 'signalling'.