And shooting retreating soldiers isn’t a war crime either. If they’re not surrendering, they are valid targets. What is a war crime is not based on vibes or feelings; it has an actual definition.
Also, yes, I would say that about Russians. Though I very much hope Ukraine prevails so we do not have to fight in Poland or the Baltics in 2032, the Russian army would be fucking foolish not to shoot retreating Ukrainian soldiers right in the back. As already noted, that is not and never has been a war crime. It is simply how war is conducted if one wants to win.
People get angry that words have meanings and that what’s true or not is not just based on vague notions of propriety picked up from TikTok. Too bad for them.