Hello Sandra
We have been using the Tangan all-purpose bags for some time. They work perfectly and are much cheaper. We gladly accept the small extra effort for changing the bags because of the price difference.
Unfortunately I can't tell you exactly which bags we use (in litres) as I'm not at home at the moment - but I'm sure you'll find them here at Galaxus or in your local Migros.
Greetings Dominic

Found the holy grail on Temu:

Aleto Sustainable Diaper Bag Refills - 4/8pcs

Here is a great alternative I found on Amazon:

https://www.amazon.de/-...

For those of you who have tested other bags, which did you choose in the end?

Hello Sandra, yes, you're right. Just do a Google search for it. You're sure to find what you're looking for.