FWIW I don't have the actual Trainline app installed at the moment, but here's an example from the LNR app. Only on the summary screen (and under Show Details, but only after you scroll all the way down past all the "legalese") is there an indication of TOC specificity of a given ticket, and in small text, too. I do really think this is not good enough, and so the OP really should make a formal complaint if the Trainline app doesn't make it clear.
However this doesn't affect the fact that the fare for travel on LNER is due (plus, now, the admin fee).