As the Dishwasher Man, but not necessarily known here for being the Dishwasher Man, here's a short thread to explain my whole thing about detergent pods:
Dishwashers are simple machines. They fill with a small quantity of water, use a pump to force that water through spray arms, and those arms spray your dishes with the water. That's really all that's happening at a very basic level.
Key to making this actually clean your dishes is chemical detergents to break down food stuff.
Now, over the course of a cleaning cycle, your dishwasher will fill with water, pump it around for some time, then drain it several times. Every time it drains, it's getting rid of food debris the water picked up.
But it's also getting rid of whatever detergent is in the water.
This is why your dishwasher has a detergent dispenser: it wants to wash for a short while to get the big food chunks off and pumped away before it spends the bulk of its time washing with soapy water.
If it didn't have a way to hold detergent back and release it later, it would all be gone after the first fill and drain (which is known as the pre-wash).
Now, because the people who made dishwashers are smart folks, they know that ideally there should be at least some detergent in that pre-wash. That's when the plates/cookware is at its very dirtiest, after all, and adding a little soap to break down those oils would help.
That's why this dispenser has a divot in the lid. It's for that.
This dishwasher spends 10 minutes washing, then drains and fills again before it opens that dispenser.
So if you use a detergent pod, those first 10 minutes of washing will be done with nothing but water.
Now, that can still do a lot! And you may be having fine results with your pods. But by not tackling the fats and oils in the first fill, the detergent has to work harder in the main wash cycle. Encapsulating oil particles uses it up and makes it less effective.
So this is why I have a beef with pods/tablets/what have you.
They're more expensive for a product that only kind of respects how dishwashers work. A product that explicitly prevents you from experimenting to see how far you can stretch your detergent. A product which encourages mindless consumption with extra packaging, to boot.
Or you could just get a paper box with some powder in it for $5 and it'll last you months.
Fin
@aymm since you're based in Germany, I don't know if this would apply - but over here the recommendations that are given in dishwasher manuals are paid for. It even says on the packaging of the detergent products that the recommendations are part of co-marketing agreements.
I would not put it past them to recommend the most profitable-for-the-detergent companies product and not the actually best one.
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äymm 
Andrew Price