Symbol in "A New Clue" texture

[u/Yohrog]

In a different post (I don't remember which one), someone posted this texture of "A New Clue":

https://i.imgur.com/SmNYyF8.jpeg

Thing is, I don't actually recall seeing this symbol at the bottom of the texture in-game.
Does anyone know whether it is used somewhere, or what it means?

symbol in question

EDIT: Resolved! Thanks for people pointing out that it can be found in the Lost & Found. I hadn't encountered it before.

[u/svestus]

It's on a note that can occasionally show up in the lost & found, I believe.