From the Cleveland Clinic (I’d like to know how they determined this):

There are some other things we know about déjà vu, though researchers aren’t exactly sure why. For example, you’re more susceptible to déjà vu if you:

Have a high level of education.
Travel a lot.
Remember your dreams.
Hold liberal beliefs.

and

Experiencing déjà vu doesn’t mean you’re having a seizure. In some cases, though, it can be a symptom of temporal lobe epilepsy, a seizure disorder that starts in the temporal lobe area of your brain.

(more)

I have left temporal lobe epilepsy, but only experience vujà dé (the feeling I’ve experienced none of this in my life ever). /s

Deja Vu: What It Is and Why It Happens

“Healthy people can experience this, but it can also be a symptom of a neurological issue”

(I’m thinking “can be a symptom of a neurological issue” fits in with “extremely rare”)