It's not liberalism. DiFi is a multimillionaire corporatist swamp-dwelling establishment swindler and Bernie Sanders is as much a swamp-drainer as Trump is. The Democratic establishment were successful at hobbling Sander's run whereas the GOP establishment failed with Trump.
Sanders is vindictive evil man. Difi was the witch’s ally and helped derail him simple as that. And yes you know your party left the rails when Difi isn’t liberal enough.