Watching leftists talk about history is wild if you actually understand history.
There's the obvious stuff, like...
But when you get into the minutiae, it's even more ridiculous.
I've seen people excuse Japanese imperialism + war crimes + crimes against humanity + arguably several genocides as being the product of Japanese Westernization.
Nope. Go look up the Imjin War, then look up State Shinto.
Vietnam has famously been fighting a no-holds-barred fight against imperialist domination for big chunks of its history. Less well-known is Vietnamese imperialism in Laos and Cambodia, both historically and in the modern era.
Literally everyone does it. Large, small, rich, poor, monarchy, republic, dictator, colonizer, ex-colony, current colony. Imperialism dates back to the very first organized human states. It is older than recorded history itself.
Also, where is this idea coming from that humans need racism to justify atrocities? Murder, rape, and pillage have literally always been a component of human warfare. Going back to everyone's favorite non-Western imperialists, Japan was absolutely brutal in the Imjin War (1592-98), so much so that Korean resistance in the Imjin War is a strong contender for Korea's national founding myth. The Mongols were infamously vicious in their conquest of Asia. Hell, one of history's long-running memes is how the average imperial Chinese civil war rivals the First World War in death count.
That's not a joke, by the way. The War of the Three Kingdoms, the Taiping Rebellion, and the Qing conquest of China all comfortably surpass World War I in death toll. The War of the Three Kingdoms also wiped out about 15% of the g l o b a l p o p u l a t i o n at the time.
(Unrelated, but the smallpox blanket incidents have been massively overblown. They were a) very rare and b) likely ineffective. Smallpox is mostly transmitted through respiratory expulsions not fomites, i.e. touching contaminated surfaces/objects. This isn't to downplay the vileness of such acts but to put them in context. Smallpox is basically humanity's nemesis. It had absolutely no problem decimating America's native population all by itself.)