Fun Fact/Factoid, use to be true, but like everything else, we've used it wrong for so long it's considered to be either

A factoid was originally defined to mean a false statement presented as a fact.[1][2] In colloquial speech, it is often used to mean a true but brief or trivial item of news or information (which can be less ambiguously described as a "factlet").

https://en.wikipedia.org/wiki/Factoid

an insignificant or trivial fact.

something fictitious or unsubstantiated that is presented as fact, devised especially to gain publicity and accepted because of constant repetition.

https://www.dictionary.com/browse/factoid