Because US/NATO is famously good at winning wars?

Actually yes - if there is an actual military to fight against. If there is a Guerilla type of conflict, it’s harder for a regular military to win.

Their weaponry and tactics have been exposed as shit in this conflict.

Some of the tactics don’t work if things like Air Superiority are not held.

Haven’t they just lost to subsistence farmers in Afghanistan?

I already talked about the Guerilla tactics… and to throw some whataboutism in: didn’t even the USSR have „bad luck“ in Afghanistan?

Except all the people liberated from the Nazis in Ukraine who are no longer living in fear of ethnic cleansing.

Yeah, russian „liberation“ often means killing everyone in sight, so yeah, they „liberated“ a big chunk of the Ukrainian civilian population. That’s what those war crime tribunals will be for, when those Russian fascists have lost the war.