You and I know that the featured snippets that come up in Google, espesially for the more generic queries, can rotate between different sites often. One day your site might be displayed for a featured snippet and then the next, it might not show up at all.
That is just what we've learned to deal with when it comes to how featured snippets behave.
Gary Illyes said the other day on Twitter that just like Google updates their algorithms all the time, they also update the "featured snippet selectors." I guess the featured snippet selectors are the algorithms that power which snippets are selected for being featured in Google.
I guess Google adjusts which queries should show the snippets, how authoritative the site should be, what type of content should be selected and so forth.
We do know that the sentence compression part of these featured snippets are somewhat powered by machine learning.
Forum discussion at Twitter.
This post was scheduled to go live today but was written earlier - I am currently offline today.