Someone please explain Bishops Opening Berlin Defense Ne3

My opponent opened like this:

But later I looked and Stockfish (depth=22) says top move is 3...Nxe4 (-1.47).

There are three games in database with this opening, though strangely none of them respond with 3...Nxe4. Is this....legit?

https://www.chess.com/openings/Bishops-Opening-Berlin-Defense-3.Ne2

Look at their ratings

😉

The pawn is for free.

i think you just need to calculate whether you can take the pawn safely or not and that's it. you should be able to see whether ne2 threatens something or not directly, as if not, it looks awful as it blocks the queen and the e-file.

It's a blunder and Black wins a pawn.

The 3 games in the database started via another move order. Black played 2... Nc6 or 2... d6 and then 3... Nf6 so the database shows it as a transposition to these games.

When you see an opening that you've never seen before and are quite sure it's not a normal way of playing, play as active and straightforward as you can. In some lines that means attacking the center immediately or not taking a pawn and going for rapid development. In this instance, your only really active possibility is to take the pawn and then take over that center with d5. If it does turn out to be a trap, at least you've seen it now and know better next time.