Below are the results for the search "What is a YouTuber?"

[robiulhasan]

In this case, a featured snippet was displayed in the form of an excerpt from Wikipedia.

In this way, featured snippets contain information excerpted from websites communication directors mailing lead selected by Google .

Emphasis Spenit

Also, featured snippets may or may not be displayed.
For example, if you search for "Youtuber" as shown below, the featured snippet will not be displayed.

YouTuber

According to Search Console Help "Featured snippets in search results" , featured snippets are displayed when a search keyword is determined to be a question
. Featured snippets are a feature that allows you to provide an immediate answer to a user's question.