If the banks suddenly withdrew their loans from Great Britain and France, that would incur a major economic crisis, would it not?
It is useful to go through the process of what happened financially. For the first 3-6 months of the war, no one took the possibility it would be a long war seriously. Ships are continuing the prewar practice of settling up each leg of the journey with gold in the hold. For example, if a Manchester to NYC ship load 200,000 USD more of goods than it unloads, it also leaves behind 10,000 ounce of gold. You can read about a German merchant ship trapped in Bar Harbor main for a fascinating example of this practice. Ships are starting to get sunk, a little at least. UK is not export goods, so gold flows are unfavorable. Roughly six months into the war, the UK addresses this issue. March 1915 comes to mind, but it could have been another month. If you are a British citizen, you have to sell all assets in the USA to the British government for paper bonds that are only repayable after the war. Fairly long duration bonds. The assets having to be sold included all real estate, bonds, and stock owned in the USA. The British government then begins what becomes the two year process of liquidating these assets. JP Morgan was the main agent, but there had to be a lot more. So say there was a cattle ranch in Texas. An US agent working for the UK would sell this ranch to an American. The funds are deposit in JP Morgan Bank. When the ship is loaded with cargo, JP Morgan will settle the difference. No gold has to be moved. IOTL, the USA would do similar action with War Bonds that would partially lead to the partial default by FDR. ITTL, the USA has no issues. Excluding the initial time period, there is no large transfer of currency (gold and silver) to the USA, just a massive change in ownership of property. I guess the best way to describe it in modern times would be take an ASB scenario. Imagine that if over 2 years, everything owned in the USA by both China and Japan is transferred to an American for existing exports sold at 6 times market value. After, two years, this ends since all the assets are used up. You get a sharp but short USA recession, and then things go back to a good place.
Included in these debts was a very large net debt from the USA to the UK still around from the civil war. The USA also ran a sustained trade surplus with the UK in things such as food, minerals, and other trade goods. The net effect is that the USA was exporting food and raw materials to the UK as interest payments on the US Civil War. All these bonds/stocks are used up, and the UK has a massive issue that it can't pay for the food and raw materials it needs so badly post war. So ITTL, the USA will largely get locked out of the UK trade zone due to the lack of exports/gold in the UK trade zone to pay for US imports. The UK is a two currency system much like OTL Soviet Union. The UK paper money will not be accepted outside the UK, so the UK can only buy with gold/silver/USD. The UK, of course, can buy unlimited amounts in its empire because it can fiat the paper money as real money.
The German trade zone is harder to predict, but it is also likely protectionist. And there is a good chance that the German zone has no colonies. There will be a tendency for the world to split into at least three trade zones. British Empire, German Zone, and US Zone. What France does is hard to call. It could be a part of the British Zone, German Zone, or its own Zone. Russia is another hard call. As is China, which to me, looks like a likely place for a major war.