lio13 Thanks for that very useful data point and also the quote, which triggered the notification. I see that my last post here is from 2023 and it's probably useful to mention, that about 1 year ago I actually used the valet voucher to leave a car at the airport for... 2 days!
Of course, since the voucher only grants you a single day for free, I obviously had to pay, but then the value of the voucher gets applied and the additional day "only" costs the difference between day #1 and day #2, which is just 20€ (last year it was 55€ for 1 day, which was also the value of the voucher, and 75€ for 2 days, in the meantime I see prices have gone up to 60€ and 80€ respectively, but the difference remains at 20€).
Considering that you also get fast track with it for free and that we were actually on a cheap Sky Express flight (so no A3 G benefits), it rendered the cost to effectively 10-12€ for 2 days, a great price for that service, not matter how you look at it.

What did make an impression on me though, was the fact, that there was only a single free spot in the (relatively long) "line" of parked cars (which the valets then move to a different parking area). I just hope the staff will help someone out if there is no spot at all, so that you don't need to rush to make your flight in the end because of that lack of a spot.

The website also mentions a 10€ discount from 50€ of purchases (though supposedly expired in April) and also free charging of electric vehicles (which, if you own or if you've rented one, would effectively mean the 2nd day is also completely free and if it's a big battery and nearly empty, then even the 3rd day would effectively be free, since the prices at the airport's chargers are at the very least 0,40-0,45€/kWh).