Germany will owe money...to herself. She borrowed internally and printed money to pay for the war, though there was some trading with neutrals that drew down her foreign exchange stocks. Still, Germany was far better off financially, because she owed money almost exclusively internally, lent far less to her allies than Britain did, AND, perhaps most importantly, had a huge manufacturing base that Britain did not.
Britain's wealth was primarily based on her financial sector in 1914, but she had lent out her money to her allies and borrowed heavily from the US, literally mortgaging her gold stocks, on which the currency was based, to US private banks that held the entire stock in their vaults.
Plus Germany built up a major new industry for the post war world: nitrates. Because of nitrate fixing to get around the lack of imports from Chile, Germany became the sole supplier in Europe, because Chilean nitrates were too expensive in comparison. Coupled with her irreplaceable industrial goods, especially chemicals, which the world was desperate for during the war, as Germany was the only source, Germany can rebuild her foreign exchange stocks without too much of a delay thanks to being able to sell all of her goods either to her new markets or the world that had been denied them without anyone filling the void. Beyond that Germany also could put off paying her internal creditors if necessary, while feasting on the 1920s boom of Congolese goods that made Belgium rich IOTL.
Also Germany won't lose the patents for inventions that the Allies IOTL harvested from her in 1919 at Versailles, which cost Germany huge income. Germany had the world's second largest merchant shipping fleet which was seized IOTL at Versailles along with huge amounts of other capital investments. Here that won't happen and Germany can continue to focus on exporting industrial goods.
Britain however will have her financial sector depleted and unable to recollect its loans quickly if at all, especially if Germany is squeezing France, Italy, and Russia, which were Britain's debtees. Britain primarily exported finished consumer goods in contrast to Germany's heavy industry, so would find that the US had filled that void in the meantime. With her primary industries weakened and having competition they weren't used to, both Britain and France will be in a bad way post war. They won't be broke or unable to compete, but will not have their pre-war economic strength, while Germany has just grabbed all the things her economy needed, so will have a base to expand on in the 1920s and exceed her 1914 potential by the mid-1920s. I'm not saying Germany will be recovering in 1918 or 1919 or even 1922, but by 1925-6 Germany is going to be relatively stronger than Britain by a wide margin relative to 1914. Its only going to get worse from there. Remember that IOTL 1939 Britain still hadn't even recovered her financial position of 1914.
OTL example:
https://en.wikipedia.org/wiki/History_of_the_United_Kingdom#Interwar_era
Germany would top her by a wide margin ITTL and did pre-war IOTL anyway. IOTL post war German industry was purposely hobbled so it couldn't compete with Britain, yet Britain STILL was falling behind. Here it would be worse without Germany being in Civil War, looted, having huge tariffs against her products, having her former cheap supplier of raw materials (Russia) cut off, and mired in war debt she couldn't pay off.