Mao Zedong when he suddenly finds out the KMT that had been slaughtering communists in a civil war before the Japanese invasion forced them into a United Front was actually anticommunist: “Welp, pack it home fellas, this changes everything. Best let the Chinese people become slaves to a foreign invader.”
I don't know this particular page, but Wikipedia "ideology" sidebar sections are pretty well known for Western chavanism editing bullshit. To add this to a sidebar, really we should have a source that says "one of the ideologies of Hamas is anti-communim", but the source is always a BBC article where one politician says something vaguely anti communist.
Don’t look at the EFF’s page worst mistake of my life