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.
Their realization with Iraq is not "we shouldn't have supported the war", it is "we should be in charge of it, not GW Bush, who screwed it up by not going full Thomas Friedman SUCK ON THIS mode".
That is why Biden and Clinton supporting the Iraq war lost them zero votes in the Dem primary, since the libs don't blame them for the war because Bush is the one who fucked it up. Should have sent more troops!
As usual with broad sweeping claims like this, i think that heavily depends on the liberal in question. Though i do agree that liberals opinions on Iraq would be different if Gore had been president during it (though idk if Gore would have invaded Iraq or not)
Just look at Lib opinions on Lib wars like Libya and Syria. They still hold their imperialist chauvinist views after being proven monstrous and empowering jihadists. They will never turn on Obama or his actions, it's too core to their identity
Sure, but all those same libs then supported Libya, Yemen etc. So their intentions are clear. They consider Libya a success because all the goals were achieved.