It isn’t a clash of civilizations between the swaggering, manly Orthodox Christian Russians and the secular, feminized West. There are no significant cultural differences between Russians and Ukrainians (after all, that was part of Putin’s rationale for the war), and the nearest NATO country, Poland, is as militant about LGBTQ issues as Russia.
It also isn’t a war between liberal democracy and autocracy, although that argument is closer to the mark than the clash of civilizations model. Ukraine has historically been dominated by oligarchs, and is hardly a perfect example of liberal democracy. Putin probably worries that the existence of personal freedoms and free elections in a neighboring state creates a bad example for his people, but it is unlikely that the Ukrainian system represents any sort of existential threat to his kleptocracy.
No, this is an imperialist war to recreate the Russian Empire over the objections of Russia’s neighbors and in violation of modern international norms. That is plenty of reason to oppose it.