The launch of the Soviet Ostrogozhsk–Rossosh offensive, which was mainly directed at the Hungarian 2nd Army (as well as partially against the Italian 8th). "The Hungarian army is not capable to participate in such a remote operation, neither mentally, nor organizationally" wrote the Hungarian chief of staff, after meeting with Keitel, when the sending of the 2nd Army was planned. Regardless, Horthy personally promised Hungarian participation in the planned 1942 spring offensive. That was after Ribbentrop and Keitel applied big pressure in January '42. Ribbentrop threatened with resetting the border revisions we received, while Keitel assured the Hungarian generals that Romania would send more troops than them, so there would be no danger of a backstab. Which of course was true. Actually, Keitel used the "Hungarian army will be in Russia" argument to convince the Romanians on sending their guys.
It seems highly likely that the leadership was fully aware of the risks involved. They made sure that conscripts would arrive from all parts of the country (to balance the distribution of future losses). No district was to conscript more than 20% of it's eligible population, and they preferred the 30-45 age group. (My grandmother used to tell me that this was the local impression at the time as well - not the youngest and strongest was taken)
Even getting to the Don was very painful. They lacked heavy armaments and basic equipment. By the time the got dug in at the river (they failed to take 3 Soviet bridgeheads), their lost half their armor, all of their artillery. Local reports by officers complained about lack of basic equipment for defensive preparations, like shovels, barbed wire, etc. During the autumn some replacements were sent, but not nearly all of the new conscripts could receive rifles, had to be equipped with surplus and remnants at the front.
Food supply was under German authority, and it's hardly surprising it was lacking. Supply depots were 100 kilometers back, and not only abysmal road conditions delayed their delivery, but they tried to "save them for worse times". With the onset of winter all that became worse. Supply got even harder to get to the troops, because horses were taken back from the first lines. Winter clothing was severely lacking.
When the Soviet attack came, a lot of the Hungarian rifles were simply frozen and unusable. There were very little anti-tank weaponry, and what they had was inefficient against the T34s. The rout was complete, which was hardly surprising of course. Command tried to restore order with draconian measures. Military police was unleashed on the retreating Hungarians, with a few cases of mass executions of everyone who had no rifle on him.