I usually classify Post Modern art as deconstructional art post WWII. It was initially fueled by the ennui of two world wars, and then drifted into cries about consumerism. Either way you get a pretty bleak outlook.
And also bankrolled by the CIA as a psy-op tool during the Cold war.
https://news.artnet.com/art-world/artcurious-cia-art-excerpt...