You don’t know the history of that area very well do you? Ukraine was around before Russia. So Russia isn’t trying to “win back its old territory”. Next Ukraine was never under the rule of the Russian Federation, and never belonged to them.
Originally, Russia belonged to Ukraine.
Russia can’t just pick some point in history and have everything that came before, mean nothing. If that’s the case, Sweden picks 1648 and St. Petersburg belongs to them.