And that’s where courts will just classify you as noncommercial.
If you don’t make enough with it to finance your lifestyle, it’s very likely not really commercial.
I'm not sure what a court would think about 10€/m, but I guess 100€/m would be considered commercial.
EDIT: the common description of being commercial in Germany is: a planned, longer term acting to make money - it's not even necessary to make a profit. Source (in German): http://www.it-recht-kanzlei.de/verbraucher-unternehmer.html
You can’t sue the parents of a kid selling lemonade in their frontyard, even though it’d technically be a violation of the Lebensmittelverordnung.
Just like a small webblog which does not even qualify as Nebeneinkunft, and which is not taxable, would also be not relevant for such a case, unless you published it knowing it was illegal to make that money.