The claimed figures are arguably too clean. Wouldn't be surprising if it was a bad/fake poll. If 1/5 of young people were really Holocaust deniers, we'd absolutely hear about those types of people all the time.

I doubt it. Probably has to do with incomplete/bad education. I imagine we would average similarly badly when asked about other WWII era trivia.

Here’s an article on Holocaust knowledge across the US from 2020: https://www.pewresearch.org/religion/2020/01/22/what-americans-know-about-the-holocaust/

I was educated in the US public school system in the mid 2010s and I felt like history class was 1/4 American slavery, 1/4 trail of tears, 1/4 revolutionary war, and 1/4 holocaust across middle and high school. Apparently that’s not normal, or the other kids weren’t absorbing anything.

The world is not getting more stupid, cross-generational memory has always been flawed. If we want to give new generations the tools to build a better future, we either need to teach them to learn from our collective experience (history) or to think of consequences ahead of time (futurology and ethics). Otherwise they are doomed to repeat the same mistakes.