Rules in war? This entire war is already illegal. Russia shouldn't even be in Ukraine in the first place. And yes, if you're a frontline reporter, then it might happen that you end up in the crossfire, especially from artillery fire. Or do you think Ukraine saw some reporter through their drones and decided to target them? Stop being an apologist for Russia's aggression.
Edit: Also, Russia does not even have a free press, and with that they don't actually have reporters, but propagandists.