What does that mean? It seems like a contradiction in terms. How could you have someone who rejects modernist ideology but promotes a modernist ideology?
It is. The ideology that's referring to which is popular amongst politically active young people is frankly a mess. In particular there's a gaping hole in their post-modernism where they just completely fail to apply any of its tools to their own ideological beliefs or power structures, instead using it to prop up their vaguely Marxist and not so vaguely anti-Western ideology.
Anyone who ever actually read Foucault would instantly realize he wasn't a Marxist because he thought it failed to sufficiently describe why the way we produce truth and knowledge shift historically, which more often than not tends to only be explainable as 'progress' after the fact.
There's a bit more nuance if you want to try to take the term at face value. DDG renders this, which seems reasonable https://areomagazine.com/2022/04/11/is-postmodernism-neo-mar...