One doesn't need to delve morality to figure this out: empirical evidence alone is sufficient to come to the same conclusion. Russia's initial invasion of Ukraine was in 2014, and it still wants more than the Donbas.
Assuming the best goes against existing evidence. Russia has not explicitly said what the limits to its aggression are. Without invoking morality, why would you assume Ukraine is the limit?
You only know what they tell you and what your intelligence agencies can uncover. Russia said Ukraine joining NATO was a red line in diplomatic discourse and then they acted on it. Same way the USA told China that aiding Russia in this war would be a red line and China has refrained from providing direct aid even after what happened in Taiwan recently. I don't have any access to classified information so no idea what information is in there but hopefully it's a lot more accurate then what we can read on twitter and Reddit.
They acted on what exactly, considering that - as far as I know - Ukraine is not a NATO member?
As a result of this war, Finland and Sweden joined NATO, turning the Baltic Sea into NATO's internal waters, which isolates Kaliningrad and St Petersburg. Ukraine will sooner or later join it too. The whole western border from Sochi to Murmansk (except puppet state Belarus) will soon be in a mutual defence pact against further Russian aggression. So in this dimension, it's been a spectacular failure for Russia.
The argument of protecting Russians in Ukraine has become morbid at best, after Russia razed to the ground several major cities with large Russian populations, many of whom now lie in nameless mass graves. Daily missile attacks on civilians in eastern Ukraine, where disproportional number of Russians live, doesn't help the case either. After the spectacular counteroffensive, which expelled Russians from Kharkiv region, they have nothing left but threats of widening the war against civilians in pursuit of scorched-earth policy.
So what justifications of this war remain? What halftones are there to discuss? That maybe there still remain some undiscovered arguments in support of blowing up hospitals and power stations?
[1] https://twitter.com/DAlperovitch/status/1570808500053475331
It's not certain but assuming the worst is just an extension of the same moral pure-good and pure-evil that this thread is about. My point is that if your view of the world is that Russia is an pure-evil actor that will keep invading more and more countries no matter what the west does then it'll eventually lead to nuclear war. In which case none of this discussion matters. The reason Finland (or any country) is joining NATO is because it makes that point explicit.