Just upgraded to WordPress 5.0 and found a strange problem of theme customize live preview showing some domain Ad website instead of my own site. 

Googling around shows nothing useful but quite a few sites have similar domain advertising site description listed in the Google search results, which means they got hijacked too.

By disabling the plugins one-by-one, it turns out that Akismet3 is the culprit which shows version 3.9.9 from wordpress.com without “view details” link. Don’t know how it got installed. The official one should be Akismet Anti-Spam, version 4.1, from Automattic, and with “view details” prompting the plugin introduction.