Discover is Lufthansa Group, but the onboard service is a bit simpler than mainline Lufthansa or SWISS.
On a long haul like Europe to Cancun, you’ll get two meals included. One main meal after departure and a second lighter meal before landing. Snacks and water are available in between, and you can ask the crew if you need something, but it’s not the constant snack parade you might be used to on Lufthansa.
It’s not a low cost setup. You won’t be charged for water or basic drinks, but expectations should be closer to “streamlined leisure airline” than full service legacy.
Totally fine for the length of the flight, just a bit more no frills compared to Lufthansa.