Here are some of the reasons why Germany was so upset about the Treaty of Versailles:
Territorial losses: Germany lost a significant amount of territory as a result of the treaty, including Alsace-Lorraine to France, Eupen-Malmédy to Belgium, North Schleswig to Denmark, and West Prussia, Posen, and Upper Silesia to Poland. These losses were seen as a betrayal of the German people, who had been promised that they would not lose any territory after the war.
Reparations: Germany was required to pay reparations to the Allied Powers in the amount of 132 billion gold marks (equivalent to about $33 billion at the time). These reparations were seen as excessive and impossible for Germany to pay, and they contributed to the economic instability that led to the rise of the Nazis.
War guilt clause: The treaty included a clause that stated that Germany was solely responsible for starting World War I. This clause was seen as humiliating by many Germans, who believed that they had been unfairly blamed for the war.
Disarmament: The treaty severely limited the size of the German military, and it prohibited Germany from having an air force, submarines, or tanks. These restrictions were seen as a threat to Germany's security, and they contributed to the sense of resentment that many Germans felt towards the Allied Powers.
In conclusion, the Treaty of Versailles was seen as unfair and punitive by many Germans, and it contributed to the rise of Adolf Hitler and the Nazi Party in Germany.