Eurowings Christmas promo - free middle seats

[Mattg]

Eurowings is running an interesting promo over Christmas & New Year. All passengers on its flights within Germany, Austria & Switzerland can reserve an empty middle seat next to their aisle or window seat for no extra charge.

https://www.eurowings.com/en/information/on-board/seat-reservations/free-middle-seat.html

I guess it wouldn't cost too much if many flights are half-empty anyway?