Duplicate content issue with home page and country code version – Magento 2

Problem is, that SEO tools tell us, we have duplicate content with Home Page URL and Home Page URL with country code.

www.XYZ.com
www.XYZ.com/de/

What is the easiest and most pragmatic solution to solve this?

Other store views ok as per

www.XYZ.com/en/
www.XYZ.com/es/ and country code needed to added.

But for the main page, I want to have only one main page.

Any hint appreciated.