At the bottom of Flow boards, there should be a "There are no older topics" message. (added in T69653 ) It is missing in pages that have topics added with infinite scroll.
(example pages)
- https://ca.wikipedia.org/wiki/Viquip%C3%A8dia:La_taverna/Ajuda
- https://www.mediawiki.org/wiki/User_talk:Qgil-WMF
- http://en.wikipedia.beta.wmflabs.org/wiki/Talk:Flow
However, the message does exist at the short (1 page, no extra loading)
http://ca.wikipedia.beta.wmflabs.org/wiki/Discussi%C3%B3:Flow and https://www.mediawiki.org/wiki/User_talk:Mattflaschen