Well, that;s why I said "If Russia use nuke on Ukraine" then all bets are off.If nuclear plants in Kursk go awry, then both Russia and Ukraine and neighbouring countries will be impacted.
That plant is closer to Moscow than Kyiv, that mean Ukraine have a nuclear mean to retaliate, and that should have shut up Russia nuclear threat for a while, there are no more Russian "red line" at least as long as Ukraine held Sudzha, and NATO probably already had picked up on that, and probably will increase their aid in the future