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.
Another key reason it's different - US troop involvement. A bipartisan part of anti Iraq war movements was the 'save our troops' angle, lamenting the poor American soldiers who stepped on mines while destroying Iraq.
Ukraine, with it's new labour laws, and banderite sympathies will be either be under Ukrainian control a derelict country of exploited people, many scarred physically and mentally by war, with no social safety net. They will undergo an 'economic miracle' and the libs will say job done, when the miracle is really just further reappropriation of wealth to the rich through cheap labour. The top 1% and foreign 'investors' will make millions while the people starve. Under Russian control, probably much the same, but with a fuse lit, ticking away until the war starts again with new funding. The cycle may repeat.