If you live in Germany but operate a UK company and all those profits never leave the UK, then you'll pay no German tax on those gains. But if you were to take those profits from the UK to use in Germany, then the German gov will want a sizable piece of your foreign gains.
From my limited understanding this is wrong and you should consult a tax advisor before attempting do set this up. “Ort der Geschäftsleitung” (smth. like “location where business decisions are made”) seems do be a recurring topic when it comes to taxation of foreign companies in Germany. They might argue you are “unbeschränkt steuerpflichtig” in Germany. (You owe taxes just like if your company was registered there.)