As a German, I now several people here who donate blood and get paid money for it (e.g. here https://www.blutspendedienst-owl.de/blutspende.html), but more people do indeed donate plasma since they get more money per session and can donate more often (e.g. here: https://www.cslplasma.de/faqs but I don't see their monetary rewards on the page anywhere).