I saved https://www.mediawiki.org/w/index.php?title=Talk:Wikimedia_Platform_Engineering&oldid=1662593 and the page, loaded after I saved, was actually still https://www.mediawiki.org/w/index.php?title=Talk:Wikimedia_Platform_Engineering&oldid=1558504 (with cached content, sidebar and everything).
It's not the first time it happens to me in the last few weeks/months, while I don't recall ever having had this issue from 2006 to 2014.