The credit card thing is only since 2018, forgot about that. Regarding PayPal, maybe it is in their TOS, but here [0] is a Screenshot from Airberlin (from an article about the new CC rules [1]) from before 2018. 7€ extra for both PayPal and CC, 5€ for SEPA and no extra cost for GiroPay.
>Also theres a german law which forbids additional fees for paying with CC.
Interesting, because lots of brick-and-mortar German businesses (especially restaurants) simply don't take credit cards, because of the processor fees. You'll go very hungry in Germany if you go there with a credit card and no way of getting any cash.
[0]: https://reisetopia.de/wp-content/uploads/2017/06/Zahlungsm%C...
[1]: https://reisetopia.de/news/abschaffung-kreditkartengebuehren...