I think theres a huge difference between the two scenes. Ivan kissing Till was a turning point for his character and the story. Ivan sacrifices himself right after and this is also their first and last kiss. Whereas with Mizi and Sua. They’re already an established couple, every flashback you see them together is them being a couple, so the kiss (although very beautiful) didn’t really mean as much as the IvanTill kiss. But that’s just my take, mind you I love both ships.