I highly doubt anyone was systematically killed.
The US had concentration camps just like Germany for their foreign populations. The difference? The allies won the war and could continue to feed their prisoners. The axis were losing on multiple fronts and had supply lines cut off. The Germans couldn’t even feed their own soldiers by the end of the war let alone POWs. Any burning that happened had to do with disinfecting from typhus. Somehow that turned into propaganda about mass burnings alive.
Reality- Auschwitz "holocaust survivor" interviews, in their own words... watch this.
https://www.youtube.com/watch?v=enDkqO1OKCc
Orchestras
Painting
Sports
Medical care
Ballet
Beer
Movie theaters
etc.
Was it a “extermination camp"? Or a POW camp where people died towards the end of the war due to starvation and disease? By all realistic accounts German POWs were treated extremely well by POW standards and they tried to keep them alive as long as possible. Hence why all the death pictures of them are skin and bones. Gassing a person doesn’t magically make you skin and bones. That’s what starving does and the Germans were cut off from supply lines. Same thing would of happened to US prisoners if we lost.