[q3k]

Are you sure this is Germany? The author has their location set to 'Amsterdam' on GH, and has no impressum on their site.

FWIW, corporate taxes in Germany aren't 50%, but 15%. What is close to 50% is personal income tax + health care if you pass a certain threshold. However, even if you're running a just sole tradership (Freier Beruf or Gewerbe), this would only be your personal income - all business expenses are not counted towards your personal income tax base and you get the VAT you paid back.

[biztos]

I would guess it’s someone with a job, and this is hitting income tax.

But corporate taxes in DE are about 30%, not 15. Don’t forget your Gewerbesteuer.