If the post-2011 generation of leftists had been less "postmodernism is bad" and more "postmodernism needs explaining", it'd be much better equipped to analyse not only Trumpism, "post-truth" politics, and social media, but also its own relation to memes and online discourse.

In fact, I often think "postmodernism" plays a similar role to what "cultural Marxism" does on the right: a sinister ideological influence which perverts minds and lead them off the correct path. This overestimation of ideas and attitudes is, arguably, itself quite "postmodern"

Anyways, read Jameson and Harvey on postmodernism for starters, but beware of their totalizing, periodizing claims, which imo are the opposite of helpful

And similarly, if you stop reading people with the "are they right in everything/overall"-glasses on, and start looking for how their right or insightful in a limited, circumscribed or symptomatic ways, than you can also read Lyotard and Baudrillard and get much out of it.