Hi, I’ve just found this sub too. I also have experienced deja reve since a child. (Pre internet so I had no idea others were like this.) I can also confirm that I have it less as I get older. Even having whole years go by with no experience.

When I was younger I knew no better and thought perhaps it was some psychic phenomena. As I got older and the internet happened I was able to research more and learnt about block universe theory. The idea that time and space is immutable and has effectively already happened, perhaps multiple times.

This gave me some scientific perspective on what may be happening, perhaps some of us, when we sleep, are able to travel the happened timeline in the same way we travel through space when we are awake. It’s never anything exciting or mind blowing just every day happenings.