@JLeslie I think that @Yellowdog is conflating two things.
Kibbutzim were originally modeled on a socialist (all share for the benefit of all) model, as a means of building Israel both before and after its independence. Early kibbutzim – 1910 and on – were originally settled by Bolsheviks (there really wasn’t a ‘Communism’ back that early). Of course kibbutzim in 2020 are totally different than they were 80–100 years ago.
SO my guess is that @Yellowdog, perhaps not understanding that socialism is not communism, is applying the ‘communist’ label to Sanders, inaccurately. The republican party supporters are known for smearing people out of ignorance.
As for the “soviet” part – that’s just made up.