The "whole modern art movement"? I'm not disputing the CIA's history of nefarious dealings or infiltrating groups to put their thumb on the scale, but the scope of that claim exceeds even COINTELPRO.

What they did was support a movement already in place because they felt it helped against Communism somehow. (And the USSR was doing pretty much the same thing the other direction) And it's not like they're signing a bunch of checks "CIA" and handing them out to artists and organizers, it was soft support through foundations and museums and stuff. It doesn't detract from their work. It kinda sounds like you half-watched one YouTube video.