I’m not sure why people keep saying this.

A proxy war has nothing to do with either side being “a proxy.” It only means that one of the sides is being supported by some nations that’s not part of the war. That’s very obviously the case here.

Yes. They would. There are no “free passes” on a definition.

I get that people don’t want to associate Ukraine with the US’s horrible track record with proxy wars but the term is still just a dry political definition and the Ukraine war fits it perfectly.

It would stop being a proxy war if the US (and everyone else) cut off funding or if they actually engaged in hostilities. As long as the US (or any nation) aids Russia or Ukraine without directly participating, it’s a proxy war because that’s how proxy wars are defined.

Why is “proxy war” in scare quotes?

It’s just a war where at least one of the belligerents is supported by at least one third party. Is there anyone who doubts that the Ukraine war meets any part of that definition?