Yes. I had heard about it exactly never growing up in the US (attending “Catholic”schools for 13 years nonetheless) and, to your point, didn’t learn about it until reading a small display when I visited Dachau in Munich. Redpill to say the least, especially since I was there ostensibly to retrace my Catholic US Army infantrymen grandfathers’ (including the one with full German ancestry) steps in WWII.