Do you have other clients who are in Germany?
It appears that you do act as a registrar for .DE domains. At least, entering "ascascdasdcascascascasdcasdc.de" on the search on the front page at https://easydns.com/ offers to register it for me. It's purely a guess on my part, but I'd expect that most people who purchase .DE domains are in Germany, so if you've actually sold a few .DE domains you probably have some German customers.
That might not be enough to open you up to having to worry about German law...but it is enough that I would not dismiss that possibility out of hand.
PS: your site seems partly broken. I first tried to check for .DE on this page: https://easydns.com/domains/register/
Entering "ascascdasdcascascascasdcasdc.de" on the search there does nothing for me in Firefox. I had uBlock Origin on, so turned it off. Still nothing. Then I switched to Chrome, using a profile with no relevant extensions, and still nothing.
So instead I just went to the list below that lists all the TLDs you handle, and went through to find DE. That has a "Special Requirements" link, which doesn't do anything for me in either Firefox or Chrome.
PPS: in Firefox's console, it shows these messages for that page that isn't working right:
'Loading failed for the <script> with source “https://matomo.int.easydns.net/piwik.js”." at register:1:1
'unreachable code after return statement' at signup.js:15:1