That is not what a plot hole is. A plot hole is something that is internally inconsistent in a story. What Ben told Luke about Vader and his father is internally consistent in A New Hope. It is explained in Return of the Jedi as a certain point of view. Ben was being metaphorical. Anakin and Vader were so different as to be different people. This is something Luke carried forward to ROTJ. It is how Anakin is redeemed. So in the one film there is no issue, in the 2nd film there is doubt because it seems to that what Vader tells Luke contradicts Ben. Who do you believe, the bad guy or your mentor. But Luke knows it to be true. So for TESB is a cliff hanger thread. So Ben explains his reasoning to Luke in ROTJ. Problem solved. No plot hole.
In my experience, most things people claim to be plot holes really aren’t.