Churchill's book does mention the Holocaust. My father owned and read it. He greatly admired Churchill.

https://en.wikipedia.org/wiki/The_Second_World_War_(book_series)

Churchill buried in the endnotes a memo he sent to Eden on 11 July 1944 calling the extermination of the Jews the "greatest crime" ever committed and ordering Bomber Command to bomb the rail-lines to the Auschwitz concentration camp

The reason why Churchill didn't mention it in great detail was because he believed that continuing to talk about it would continue hate for German people, who he believed were not inherently evil, just led that way.

It's why he opposed the bombing of Dresden, despite widespread public support for area bombing the German vermin into submission that continues even now, with most people agreeing that it was morally correct to kill Nazi "civilians".

Have you read all three books yourself to confirm this? Or have a single source confirming it? No, you don't. Because this is gish gallop. Making a false point that's hard to challenge because of the sheer effort it would take to disprove it.