‘Rav Soloveitchik was once approached with information about a certain ancient and rediscovered text of the Torah, that contradicted the Torah that we have. The Rav responded to his questioner “What is your opinion of the founder of the Reform movement”? The man responded “He is an idiot, an am haaretz d’oraysa!”. The Rav said back “Do you think we have a monopoly on ameratzim deoraysa”!?’
This was probably referring to the Qumran manuscripts, which do differ slightly from our texts of the Torah (and much more from out texts of Nach). The Rav was being kind; the Qumran community were not amei haaretzim, they were out and out heretics if for no other reason than they observed the holidays on different days. This is particularly notable given today’s Daf Yomi.
A bigger challenge is that Chazal and some rishonim appear to have texts that differ slightly from ours; the resolution is that Chazal did not believe that we had perfectly accurate texts.