[Plugin: Yet Another Related Posts Plugin] YARPP as a widget is not accurate

I’ve started using YARPP recently and I’m displaying the related posts in two places: at the bottom of an article and on my right sidebar. At the bottom they are accurate, in that they are related. I was expecting to get the same or a very similar list on the widget in the sidebar, but instead it’s showing something that could as well be random.

Check this post for example: https://pupeno.com/blog/the-sad-truth-about-testing-web-applications/

Or any other post on https://pupeno.com

Any ideas why that is happening?

Thanks.