They aren’t using it as a symbol though, blowing up a religious building is not exactly a move that would be popular among russians. Which is why they’re denying that it was Russian munitions and trying to claim that it was Ukrainian anti-air missiles falling back on buildings after trying to shoot down other things. To use it as a symbol you kinda have to say it was you.
What this will become however is a symbol of reconstruction for Ukraine, which is not at all beneficial to Russia’s strategic interests. Hence why I lean to it being a mistake of some sort. Given the accuracy their missiles have though that’s hard to justify as well, unless it’s not actually the main payload of a missile and is instead one of the earlier stages that gets split, like the fuel tubes sections. This is why actually seeing the missile debris is useful, you can figure out whether it was the target or not based on whether it’s the payload section or some other part of the missile.