Generally it was just a term of abuse from Clinton supporters, but I also heard it a few times from leftists who were disappointed by the failure of many Bernie supporters to decouple from toxic masculinity in the process of veering leftwards. This was not entirely untrue - Bernie energized many ordinary young folks without changing their upbringing or prejudices. There was a nonzero contingent of Bernie supporters who were all onboard with left economic policy, but saw matters like racial justice, LGBT rights, or women's issues as 'divisive' or 'irrelevant' compared to Bernie's economic leftism.
On average, though, Bernie supporters were considerably to the left of the Dem Party in general on social issues, so the actual applicability of the term was extremely limited compared to its usage as a general term of abuse.
Christ. Remembering marching in Philly chanting Black Lives Matter in 2016... we were so full of hope back then.