I realize that this question might sound controversial. Here is why I am asking : lately I have been reading a lot on late Antiquity/early Medieval History of Europe/Middle East/Central Asia and also on China/Japan Medieval History. And these books are basically full of massacres : kingdoms and empires rising, clashing, and disappearing, cities and settlements burned to the ground, entire population exterminated or reduced to slavery, etc. It occured to me that the German campaigns in the East match these patterns quite well. But the Nazi war crimes are often presented as an historical anomaly. I guess that basically I am asking if the historians of the year 3000 will treat operation Barbarossa differently than the Avar invasion of Central Europe and Byzantine Empire in the 7th century. Note that I understand that the Holocaust, especially when it targeted German citizens, is a different matter.
Caveat: Since the question itself is speculative, the answer is going to be somewhat speculative. Apologies if this answer doesn't satisfy the subreddit requirements.
Historians can't obviously make positive assertions about how future reactions or events might play out. Whether the Nazi events are seen as anomalous however would depend in part on how the memory of these events is articulated. Thus, if the overall memory of the events that survive is to see it as a great evil, and that this memory goes on to become the dominant narrative, then the events in question will be remembered as anomalous. If the surviving record and memories however do not register these events as catastrophic, then it might not be. So if the "evils" in question become part of a narrative of triumphalism, then its unlikely that they will be regarded as anomalous.
One way to compare for instance is by looking at slightly analogous events. I'd look to the Mongols and Alexander. Please note however that as with any comparison across time periods and cultures, things don't line up perfectly. But anyway - the Mongol invasion of Baghdad and subsequent sack of the city has for instance left a legacy in historical records as something of a "great evil". While we are today engaging with the Mongols in a somewhat more neutral manner, in general the imagery of the savage mongols, of hordes overrunning cities, of mountains of skulls, etc was a particularly popular and enduring image. This is in part because the narratives condemning the Mongols and their violence remained powerful and alive, even as the Mongols faded. Contrast this to Alexander, who reduced Thebes to utter rubble (or if you want other examples, Rome in regards to the Gauls during Caesar, or Corinth even earlier). Even though primary literature from the era indicates the event was considered anomalous, the enduring legacy of it generally appears to be to disregard it, because the Alexandrian legacy is one where the event was largely justified, and thus not a "great evil" as such.
Lastly, another issue that would determine the extent to which it would be regarded as "anomalous" is the relative "fame" (or infamy) of the event. The Holocaust and Nazi war crimes receive considerable attention today, which in turn means that future generations will be more consciously aware off the legacy of condemnation, because more evidence off it might survive. In contrast, events such as the Bengal Famine in India, which also saw many millions die, are arguably more complex, and also tend to receive less emotive responses and memories for whatever reason (if you wish to compare - contrast the fact that the Jallianwala Bagh massacre where comparatively much fewer people died holds much greater sway over Indian memories) and thus in subsequent memory, while condemned doesn't receive the sort of continuing attention that the Holocaust does. In the long run? This might eventually lead to the memory of the famine "fading" into the background of history, and thus not being seen as anomalous. Events kept alive however would.
Ultimately however such things are impossible to say. We have no reliable way to judge how people a 1000 years from now will react to anything, because really, we can't even know what sort of society will exist.