@shadowhawk if the United States invests heavily in the Atlantic, they will eventually capture Normandy in a typical match. There is little that Germany can do to prevent it without sacrificing the more important objective of capturing Moscow or the Middle East to achieve the massive income swing.
Germany can either try to slow down the invasion by making it more expensive to have an adequately naval force and expeditionary landing force that can survive a Normandy landing, or merely prevent the initial beachhead to turn into an expanded mission to liberate all of France and threaten the German homeland.
Capturing Normandy and making it into an Axis territory does make it significantly harder to have as a beachhead since American planes can’t reinforce the ground forces in the first turn of capture. That is a big swing and a key weakness of the strategy to leave it in France’s ownership.
Leaving it in French control means the United States needs 3 more transports and a loaded aircraft carrier to provide equivalent benefit as a factory and an air base. That is an extra turn of Atlantic-side spending and we find the games in such tight balance that this could tip the balance of power in high-level matches with battle calculators to exploit any slight odds advantages.
Pros and cons of Germany taking Normandy. It is not a clear and simple decision. I expect the meta to continue to slowly evolve in OOB League matches, although sadly there are not enough high-level games in this setting to get the strategies to advance as quickly as before.