Deja vu is when you think something has already happened to you but are not entirely sure AND that something is happening again right now.
It's kind of like having an intuition about what happened in the past to help deal with the present. So that makes deja vu a form of precognition.
From their begins a debate about whether in the past WE knew - consciously, metaphysically, quantum physically - about the future deja vu experience (hence the meme that jokes about deja vuing having deja vu.) Some say we time travel and others say that our minds are playing tricks. Some might say that physics allows it and is meaningless like gravity.
Too complex topic. See that now. Thanks for honesty.