I really don't understand why lemmy.ml's instance description no longer has "leftist" in it as it once had.

Some communists have taken to not calling themselves "left" anymore because they see it as synonymous with "liberal" and a barrier to reaching republican voters who automatically switch off the moment they get a whiff of anything left due to programming. The intent being to shift away from left/right altogether because in american politics it's synonymous with culture war when when communists say left we mean it in economic contexts.