I found the solution in another thread Klick
I just install the metapackage scanner-supportfrom AUR and after a reboot I can scan without any problems.
On my system the package just adds the ipp-usb package. Everything else was already on my system installed. The ipp-usb package was already on my system before. My Scanner doesn’t work also, so I remove it, because I expect I don’t need it with my network scanner.
It is also interesting that the Airscan Protocol changes from WSD to eSCL after installing scanner-support.
scanimage -L
device `airscan:e0:Kyocera ECOSYS M5521cdn' is a eSCL Kyocera ECOSYS M5521cdn ip=192.168.1.90
Finally, I don’t know what the metapackage scanner-support does different than manual installation or why it works now. But my problem is solved.