Where was their support for Eastern Ukrainians against government-backed neo-Nazis in the eight years before the Russian invasion?

Actually there was a small amount of support that ultimately got crushed: The Nation, 2016: Congress Has Removed a Ban on Funding Neo-Nazis From Its Year-End Spending Bill

And so, in July of last year, Congressmen John Conyers of Michigan and Ted Yoho of Florida drew up an amendment to the House Defense Appropriations bill (HR 2685) that “limits arms, training, and other assistance to the neo-Nazi Ukrainian militia, the Azov Battalion.” It passed by a unanimous vote in the House.