There was an interesting interview with Rachel Reeves recently, where she was clear that they didn't want to make that case yet.
They were happy with the windfall tax being picked up by the Tories, but if you look at the detail of the Tory version, it's a very different beast. Labour don't want to put out a full list of commitments now, and see the Tories pick off the best ideas, and present right wing versions of them which would make it more difficult to differentiate.
She was certain that they had the ideas in place to fight an election, but when you're fighting a populist government which has a very loose relationship with ethics, they needed to be more clever with when they presented ideas.
Could be a load of bollocks, and she's bluffing, but it does make sense. It's also pretty much what every other opposition has done over the years.