For example regarding Dachau, the supposed saint Maximilien Kolbe, he was publishing anti government materials. He was warned and told to shut down his press. He disobeyed. He was told again after more published material, he was threatened and ordered to stop again. Then he kept publishing, and finally he was arrested and sent to Dachau. After 2 warnings from his lawful government he was still given mercy, and he chose to disobey. The concordat with the Vatican said that priests must stay out of politics, he disobeyed the Vatican. The false narrative that NSDAP was widespread eugencist and pagan only came about decades after the war.
The priests that died at Dachau broke the Vatican concordat and they meddled in politics. They didn't deserve death, and they weren't executed in some death camp, like LeDeg said even the jews haven't considered Dachau a death camp for decades. They died because of disease and natural causes, just like the hundreds of thousands of communists, masons, and homosexuals that, in line with catholics teaching, were removed from the population.