Russia started this when they invaded "performed a special military operation" on Ukraine - therefore Ukraine has the right to do whatever it needs to make Russia fuck off.
Hungary's and Slovakia's leaders are salty because they kept suckling on Russian oil rather than switching towards alternatives like other EU countries did - and now it's biting them hardcore in the backside.
This is a very deceptive title. The meeting was moved to different location, but they are still a part of it. The gesture has no real effect on the outcome.