Ok, so in order to answer this, it is important to differentiate between two groups (though they overlap): The prisoners the Soviets liberated in 1944 and 1945 and the Concentration Camp prisoners of Soviet nationality liberated by them and by the other Allies.

The Soviet Union was the first allied power to liberate a Concentration Camp, namely Majdanek, in June 1944. They later went on to stumble upon the remains of the former death camps, where not prisoners were left, and to liberate Auschwitz in January 1945. Albeit they were the first to liberate camps, the number of prisoners were very low. This had to do with the Nazis evacuating prisoners from these camps before the Soviets arrived (A more in-depth explanation of this can be found here by /u/kieslowskifan )

All in all the number of prisoners the Soviets liberated from Auschwitz and Majdanek numbered somewhere in between 8-10.000, most of them too ill to have been forced on a death march by the Nazis. On the whole, the Soviets treated these prisoners well, feeding them, nursing them back to health, caring for them. Especially after the war was over, the Soviets made a considerable effort to return most of them to their home countries and see them off well. They also used them as witnesses in some very early war crimes trials against German officials and officers and also collaborators they captures. The most famous one being the Soviet Majdanek trial but also a couple of smaller ones held before the war even ended.

Aside some prisoners who the Soviets regarded as political enemies (members of the Organization of Ukrainian Nationalists e.g.) and whom the Soviets either arrested or killed, the only group treated differently were liberated Soviet citizens, either those whom they themselves liberated or those liberated by the Allies and slated to be repatriated to the USSR. As a matter of Stalinist policy, all those Soviet citizens who had been forced laborers or imprisoned in Concentration Camps and survived their imprisonment were to be regarded with suspicion by the state authorities. In essence, they were seen as potential collaborators.

Every liberated Soviet citizen had to undergo questioning by the NKVD and SMERSH (the Soviet anti-spy agency, literally Smert Shpionam or Death to Spies). They questioned them about their experience and the extent of them working for the Germans. Of the Soviet citizens liberated either as Concentration Camp survivors or forced laborers, about 7% were sent to the Gulag camp system as traitors, while about 15-20% had to work in labour battalions for the Soviet Union for a couple of months or even years. Also, even if that didn't happen to you, a lot of them faced social discrimination in the Soviet Union, which could mean that you were forbidden to study at uni or that your husband or your friends would abandon you.

One of the most interesting cases illustrating how the Soviets dealt with Concentration Camp survivors is that of the Soviet officers breaking out of Mauthausen. In the Mauthausen Concentration Camp 500 Soviet POW officers who had been brought to the camp in order to be killed in what was known as the Kugelaktion (the shooting of POWs who had attempted to escape a labor camp) planned and executed a revolt in February of 1945. Kept in a seperately walled off area of the camp, they didn't have the possibility of getting themselves weapon aside from a couple of stones to throw and one fire extinguisher, so on February 2, they just straight up charged the guards basically beating some of them to death and scaring away a couple of others (imagine 500 Russians charging you like the devil personally is behind them). 419 managed to escape the camp and 300 made past the outer guard perimeter.

The SS subsequently enlisted the civilian population to hunt these people down and a couple of civilians did participate in war crimes in from of brutally lynching these men. Of these 300 who managed to escape, most were caught or murdered, mainly due to the local population being unwilling to help. A couple of families helped though and one of the officers even built himself a hut in the woods to survive until liberation. We know of at least 11 Soviet officers who survived.

Matthias Kaltenbrunner, a historian from Austria, did extensive research on this group and especially on how they interacted with Soviet authority. He found that 8 of them basically got together to tell a certain narrative of the whole event that in some details does not link up with historical reality. For example, they told Soviet authorities that the leader of the jailbreak was highly decorated (Hero of the Soviet Union) pilot who had planned the revolt and acted as its leader. However, said pilot had been already dead by the time, they broke out. They chose him because of his decorations and because he was a pilot which brought special status. Similarly, they left out details on how a small number of non-Soviet POWs were also there but not involved in the plan, rather once the outbreak started, they basically left them behind. Another detail they left out was how some survived with the help of local farmers. One of them had survived by building a hut in the wood and others claimed to have been with him, basically forming a resistance organization, which is something that also didn't happen.

What this shows is that even in cases where one would assume that it was clear that the men in question had resisted, they chose to alter the details of their story to make it more palatable to Soviet authorities.

Sources:

• Matthias Kaltenbrunner: Flucht aus dem Todesblock. Der Massenausbruch sowjetischer Offiziere aus dem Block 20 des KZ Mauthausen und die "Mühlviertler Hasenjagd". Hintergründe, Folgen, Aufarbeitung. Innsbruck [u.a.] 2012.

• Dan Stone: The Liberation of the Camps.

• Shephard, Ben. 'The Long Road Home: The Aftermath of the Second World War.' (Bodley Head, 2010).

• Stefan Hördler: Ordnung und Inferno. Das KZ-System im letzten Kriegsjahr. Göttingen: Wallstein, 2015.

• Nichaolas Wachsmann: KL. A History of the Concentration Camps.

• Anne Applebaum: Gulag.