At the bottom of every page is a footer than by default reads, for instance, like
This page was last modified on 7 June 2016, at 01:54.
There is no indication of the time zone. It would be preferable if it read something like
This page was last modified on 7 June 2016, at 01:54 (UTC).
(or the user's preferred time zone if they've set it in their preferences).
This may also apply to MediaWiki:Lastmodifiedby