The expert medical witness that the prosecution used was not sound. And lots of other medical experts have come out to say that his testimony was nonsense.
This doesn't prove her innocence, it just highlights one element of the trial that was badly orchestrated.
What they are not focusing on, is the 9 months of trial evidence that was extremely compelling. Like for instance, the 30x air tubes that had malfunctions while Letby was on duty. Yet none malfunctioned at any other time when she was off duty.
Then in her journal, she had written in the initials of each baby that had died, on the date that they had died. This is classic trophy keeping behaviour. She also wrote the following, "I AM EVIL I DID THIS, I killed them on purpose because I'm not good enough, I don't deserve to live, I am an awful person."
And even when she took to the stand, she was incapable of defending herself. Could not explain about the stuff she wrote in her journal, or text messages to other nurses after the deaths on their ward. She was fishing for sympathy from them. She was looking up the families of dead children on Facebook, for a reaction or acknowledgement of their grief.
She showed no emotion while the details of each baby was read out in court, but suddenly bawled crying when a male doctor colleague gave evidence against her. And it later became apparent that she had fancied him. So she was more upset about that than all of the dead babies which demonstrates a very warped and narcissistic behaviour.