That's the exception that proves the rule. Fact checkers rarely can be wrong. The overwhelming amount of times they are very correct.

If anyone thinks I am wrong, they can list a dozen times fact checkers were wrong.

What would this list look like? A list of posted removed for being misinformation but that were actually not? Not particularly surprising such a thing does not exist

You mean the claims being made by the Trump camp were unsubstantiated? Because that happened and they were at the time.