The data source seems pretty obvious here. It doesn't know much about atop, but your question has led it to believe that it's something available on Linux distr

The data source seems pretty obvious here. It doesn't know much about atop, but your question has led it to believe that it's something available on Linux distros, so it spat out a likely list of Linux distros based on the weighted average of linux distros listed by other projects in its training set.