I don’t think it’s been debunked at all. Jefferson (Thomas) is the most likely father. After Randolph remarried he was very rarely at Montecello but the white Hemmings children continued.
The claim was that Thomas Jefferson was proven to be the father. That claim was false. You can believe whatever you chose, but several candidates had the right DNA, the opportunity, and knew the mother.
Tom Hemmings is buried right here in the Leavenworth National Cemetery. Exhumation might provide additional evidence, but this has not been allowed.
Yes its been reported that guests at Jefferson’s dinner parties were embarrassed when served by young light skinned slaves that looked just like him.