The ridiculous claim is getting pushback now: [nature.com]

There Are failed attempts at pyramid building all over the place....they were learning as they went, clearly.....angles, weight, base vs. height, and etc

"Atlas Obscura " certainly is a very dubious place to publish a so called scientific paper anyway. Many people today though, are without are deep understanding of histories time line, and would fail to understand how extreme a claim eight to twenty thousand years is. And as the old adage goes. Extreme claims require extreme evidence.

Though having said that. Since a pyramid is just about the easiest and most obvious way to build a monumental structure, I am sure there are still many out there, mistaken for humps and hills which are yet to be discovered. And some certainly older than those in Egypt, which are not the oldest known anyway since those in Ethiopia are well known to be older.

As an aside we have a really cute one here in the UK [en.wikipedia.org]