I have heard the opposite: that the United Kingdom was, as a rule, an important ally for the economic policies favoured by Germany and others. E.g., “So far the following EU countries have announced that they oppose Eurobonds: Germany, United Kingdom, Finland and the Netherlands.” on p. 186 in Schäfer 2012 = vol. 9.2 in EJCE =
https://www.researchgate.net/publication/255726169_The_Sover...Further more, the UK was an important net contributor.
So I think, on the whole, Brexit was bad for Germany.