The Bolshevists had canceled all signatures of the former Tsarist government under international treaties and laws of war. The La Hague convention of Land warfare and the first Geneva convention were not signed by the new rulers. With less comfortable treatment states want to force opponents to sign those international conventions to oblige them to treat their POWs according to them.
The POWs captured by the Germans, including Jewish POWs, were treated according to the Geneva conventions. From the 232.000 POWs of the Western allies, 8.348 died in captivity. Those include POWs being seriously injured at capture.
Especially remarkable was the treatment of captured Air Force personnel, because the Stalag Luft's were under the command of the Luftwaffe. The German Luftwaffe interrogator Hans Scharff was the most famous. He had never even raised the voice against POWs. However he received every information he wanted to have. After the war he gave lectures in the USAF about interrogation techniques.
Nutrition was according the ratios being accessible to the German population, sometimes even better based on Red Cross relief packages. The situation worsened when at the end of war the German infrastructure collapsed.
The treatment of German POWs in Allied hands however is a dark chapter.
Eisenhower renamed them "DEF" (Disarmed Enemy Forces) to come around the Geneva conventions. The International Red Cross was not allowed to visit US POW camps in Germany until February 1946. The ICRC writes:
The ICRC made approaches to the authorities of the four occupation zones and, in the autumn of 1945, it received authorization to send both relief and delegates into the French and British zones. On 4 February 1946, the ICRC was allowed to send relief into the American zone, and on 13 April 1946 it obtained permission to extend this activity to the Soviet zone.
The quantities received by the ICRC for these captives remained very small, however. During their visits, the delegates observed that German prisoners of war were often detained in appalling conditions. They drew the attention of the authorities to this fact, and gradually succeeded in getting some improvements made.
That is hard stuff in the diplomatic language of the ICRC.More clearly conditions are described in another report:
It is estimated that 700,000 to a million men may have died within the period they spent incarcerated in American and French camps alone from 1945 to 1948. There are much higher estimates, however, and attempts to uncover the truth regarding these camps in modern times, as well as excavation of reported mass grave sites, have been vigilantly thwarted by, among others, the German government.
It is unknown how many perished under British captors but recently declassified documents indicate widespread torture and abuse. Under all of them, many of the prisoners were used to do dangerous work such as working with hazardous materials and mine sweeping in complete disregard of the law.
PS: I never was and never will be anti semitic. However the comment above made me for a short time reconsider my standpoint.