From the Guardian editorial:

Erasing the dark marks of the recent past should not mean disavowing everything that happened between 2015 and 2020. There is a danger that Mr Starmer’s determination not to allow Mr Corbyn to represent Labour at the next election comes to symbolise that stance. “The Labour party is unrecognisable from 2019 and it will never go back,” Mr Starmer said on Wednesday. “If you don’t like that, if you don’t like the changes we have made, I say the door is open and you can leave.” That sounds like a message to the hundreds of thousands of people who joined Labour in those years and the millions who voted for the party that they aren’t welcome.

To conflate the antisemitism of some on the left with all leftwing politics is illogical and shortsighted. Given the state of the country and the world, now is not the time to dismiss important ideas just because John McDonnell once smiled at them. Not only is the former shadow chancellor one of the most interesting economic thinkers in the Labour party, he was also right to oppose austerity from 2010 onwards – not a claim that can be made by all of the shadow cabinet.

Mr Starmer served in the frontbench team of his predecessor. He ran for leader promising to carry on the ideas of his predecessor. To proclaim that there is no place for Mr Corbyn in today’s Labour party, no matter what he says or does, not only looks vindictive, it poses serious questions about the consistency of the current leader – questions that his opponents will be all too happy to raise come the next general election.

The Guardian, though being on the right side of things here, is being a little polite. Vindictiveness and inconsistency is putting it mildly. There's nothing worse than the sight of a weak leader trying to act all stern and assertive, especially when that involves peddling untruths. I'd just add that the rest of the editorial, the bits I haven't quoted, contains a lot regarding "Labour antisemitism" that I vehemently disagree with.