Virtue signalling and protests both can serve an important function beyond trying to show ones worth to a group, feel good, and all that. It also signals what one finds virtuous. It's a way of expressing values, and letting people know what is important to you, and how much. Protesting takes a lot a time, effort, and a certain amount of courage. It lets people know 'I'm on the outgroup/ingroup on this topic for these people'. Topics can then be introduced into experimental groups for consensus and solution.
True which, to me anyway, makes the concept even more nebulous meaningless.
Now we don't only have to split the hair, third party no less, between a heartfelt show of support and a showy show of support but between different motives behind a heartfelt show of support.
When we've reached the point of having to define the motivation behind another motivation I can't see us in a useful place.
For example, more than a few people who I know that were outraged about the taking a knee have since learned both that taking the knee part was added to express gratitude for the troops even while criticizing the country, and that the national anthem is not to represent the armed forces, but the nation. They'd honestly never thought about it like that before a bunch of vets started saying things like, 'you know this isn't about us at all right?'.
Without letting this get too deep into a specific example which might risk hijacking this discussion or taint it with my own personal feelings about a specific example one of the things that tends to push protesting into the "overly showy and pointless" category for me is the use of symbolism that is so broad and general as to have little to no connection to what is being protested.
With zero context if someone is standing outside a gun factory holding up a sign with a picture of a gun in a circle with a line through it... you can tell what they are protesting. A person holding up a picture of a bloody fetus outside an abortion clinic, you can tell what they are protesting. Overly symbolic acts that need to be explained just don't have the same context for me.