Lukashenko regime is much more stable because their police state is much stronger, they have literal KGB and people get visits from it for doing counter-regime posts on the internet much more often than in Russia.

Ukrainian regime actually does not want the war to end. The oligarchs there are very much OK with plundering the country while playing the external enemy card. If war stopped the population would turn their attention inward and they have nothing to show for their time in power.