It gets worse.
Next we asked questions about A' terms that we knew for sure were not in the training data.
ChatGPT, using the language & semantics from domain A, fabricated definitions for A' terms which were wholly made up.
Total fabrications, complete & total hallucinations - provided with manufactured citations b/c we requested citations for the definitions of the terms.
It was an incredibly believable fabrication. Undetectable to a non-domain expert.
And totally, completely wrong.