I think a material difference between Iraq (v2 anyway) and Ukraine is that they can keep doing the "well Russia was the aggressor" thing indefinitely even if the reality is more complicated.
also yes obviously some libs are still stubborn about Iraq, the worst ones, but for the most part its generally agreed that the Iraq War was a bad thing.
I think that they will continue to do the "russia was the aggressor" but they'll almost certainly start saying "we should have negotiated sooner, it was obvious we had bad intelligence (or, if we're lucky, 'it was obvious the media was lying') about how weak the russian army/economy was"