Appeasement to end conflict versus appeasement to avoid conflict may not be exactly the same thing, but it's still appeasement. Pressing Ukraine to cede its sovereign territory to Russia as part of a peace deal is appeasement regardless of whether Russia is currently occupying the territory by force.
We don't have to keep fighting, or to do anything. But giving international recognition to Russia having a rightful claim on a portion of Ukraine that it took by force and without justification s going to embolden every autocratic power with designs on adding territory (chiefly Russia and China). Everyone recognizes that the majority of human history has involved civilizations and countries constantly attacking each other, capturing territory, ceding territory by treaty, etc. But the entire point of the post-WWII order is supposed to be that the international community agrees we're not going to do that anymore. That we've moved past that into a new age of peace and stability where national borders will no longer be changed through external force. Giving up that order and returning to an age of imperialism and territorial aggression is no small thing to do. Especially given the manpower and level of weaponry available to the potential combatants in modern imperialist wars. Even without considering the possibility of nuclear war, it's terrifying.
The world has been relatively peaceful (relative to the majority of human history - I recognize that plenty of wars and atrocities have still occurred in the post-WWII era) for the last few decades. We've essentially been living under the umbrella created by a stable, US-led world order for several decades. We've been living under that umbrella for so long that people have forgotten what the rain feels like, so they don't understand why we need the umbrella. Going back to an age where the international community does not strongly reject the very concept of imperialist aggression will have potentially disastrous consequences for us all.