Usually the fee is on merchant (and it's few % depending on region regulations etc.) Payment providers such as Wero are doing direct bank transfer, which is usually fee-less, but then they can afford to put a on-merchant fee that's much lower than what credit card companies are charging.
Thus the model is win-win-win: Consumer doesn't pay more, Merchant pays less, and Wero gets their share.
Card companies hated this. They said they'd lose money and have to pull out of the EU entirely if it passed. Turns out, they lied!
[0] https://www.mollie.com/growth/wero-payment-guide#:~:text=How...
[1] https://www.bnpparibasfortis.be/en/public/faq/how-much-does-...
Individuals is completely free. You can transfer even to people without bank accounts (and withdraw on places like corner shops and authorized merchants).
For companies certain transfers are free. eg: my company pays nothing, since I'm not a merchant, one of the banks tried to charge once and I just changed to another that offered 0% in return for keeping investments there.
Some banks offer extra services like POS machines with instant confirmation and so on (so the POS employee don't need access to the company bank account).
How much is in this case?
https://wero-wallet.eu/e-m-commerce
So they charge a fee, but they don't specify what a "small percentage" is.
That's why it's impossible to find on that link what their fee is. It's so clear that it's invisible.