Watched a video on the Hungarian - Romanian war of 1919 that led me down a Wikipedia rabbit hole of what happened to the Austro-Hungarian Empire following the end of hostilities.
At first reading, it seems as if the Treaty of Trianon caused the complete disintegration of the empire through its creation of new nation states that were each so much weaker than the sum of their former parts.
The Treaty seems to have been very harsh, similar to the Treaty of Versailles that was imposed on Germany. However, the Germans turned this anger into extreme nationalism and we had the rise of the Nazi party and the creation of an incredibly strong military within two decades.
The only reason I can think of for this not also happening in Hungary is because the Austro-Hungarian Empire was so thoroughly dissolved, with its population and industries scattered to the winds. Germany ended up with less territory too, but it was still able to bounce back incredibly fast.
The highly simplified answer is because the German Empire consisted primarily of, well... Germans. The territory it did lose generally had a non-German population majority (e.g. Northern Schleswig returned to Denmark, north-eastern Poland returned to Poland). President Woodrow Wilson was a major proponent of the self-determination of peoples in Europe, and this was viewed mostly through an ethnic lense - each ethnic group should have its own state. This is why the Austro-Hungarian Empire was partitioned as it was, because it consisted primarily of non-Austrians and thus there were many different peoples that needed their own new country. It was an empire formed and developed in the era before the ethnic nationalism of the mid-19th century, where the only unifying factor was the rather medieval conception of a foreign emperor ruling many disparate lands by virtue of age-old inheritance. This is in contrast to the German Empire, which was built in the era of nationalism by the sole desire of unifying the German people, and the German people only - they rejected a union with Austria because the nationalist leaders didn't want so many non-German peoples in their empire.