"Not the" are two words that, once followed up by a
clause, call out something or someone. Usually, it's in a comedic sense but can and is used with negative or serious intention. The 'the' is
replaceable for names, words like 'y'all', pronouns, and other
verbs.
Although its not quite clear where "not the" orginates from, it's mostly commonly used on Tiktok and Twitter.