The OP could only really have been written by someone who doesn't live in the UK and has little grasp of its politics.
Starmer assumed the Labour leadership by coasting a wave of right-slanted purges of the membership that gutted the party of any semblance of approaches that could properly address the issues the country faces. Its grey managerialist dogmatism might fly if it was coherent and was providing positive results and evidence of support in polling. It's plainly doing none of that.
That's why the initial period of Labour's term has been so fraught and electorally disastrous, to the extent that if the government doesn't change tack in fundamental ways, we're left praying that Farage and Reform implode before any general election, otherwise we're all seriously fucked.
Lashing out at Corbyn in these circumstances is pathetic. His own slated new party is undergoing its own all too predictable teething troubles, but his platforms have always been truer to leftwing thought in the UK than anything Starmer and his dwindling, flailing cabal of supporters in the Labour Party and the media currently champion. Polling when Corbyn was leader showed his policies were popular among the general public even as the man himself wasn't.
There's a reckoning coming for Starmer's Chief of Staff Morgan McSweeney and a number of other shady operators within the Labour Together group and its "Blue Labour" (note for US readers: blue is the colour of the Tories in the UK, red is the colour of Labour and the broader left) fellow travellers who were shamelessly undermining Labour and its leadership during the last but one election because they preferred to see another term of Tory government than a Labour one that might veer left of centre. I hope it comes sooner rather than later, before Reform cements any further gains.