The Left's propensity for street violence and broader intellectual justification of violence under the guise of class warfare is well known. (Of course that propensity exists on the right too.) Since the collapse of the New Left in the late 60s, the left - center left and more radical left - were successful in expelling that violent faction from their political movements. The reaction against the New Left's excesses was so pronounced that in America it acquired the name of 'hippy punching' - a reflexive condemnation of anything that had even a whiff of radicalism. It was a hard earned piece of institutional wisdom. In the past few years we've seen the last living repositories of that wisdom cycle out of the left's leadership roles, both in and out of government and the result IMO has been a marked rise in the tolerance of violent, vicious, extreme, rhetoric on the left.
All this is to say that it's an old but resurgent phenomena. I, like other's have mentioned, am appalled by on line left spaces, no one who frequents them can deny the rise post 2020. I'd point out that this is not diatribe against the left as a broad necessary ideological orientation, as the right, as noted has its own problem with violence, but with a different dynamic. It's a profound misfortune that at this moment when we need a sane and sober left, we're seeing this spreading dysfunction. It's one of the reasons, for all his faults, I'm a strong supporter of Starmer as I think he sees this clearly.