It's getting more and more confusing:
Washington Post claims that
Postal worker recanted allegations of ballot tampering, officials say
(I couldn't read that article it's not free, I read a Dutch transcription of it)
However Foxnews has embedded a tweet of the whistle-blower where he claims that
he did not recant and that WaPo should recant
Edit:
Here is an analysis by a local reporter about the Erie postal fraud. Even if it's true, it's a very tiny amount of ballots that it would not have made any impact on the total count. Which doesn't mean that it shouldn't have happened, if it did happen at all