I just noticed this on MSE homepage:
Time stamp match, but not the user doing the action.
Digging a bit further, turns out it's because of automatic non-bumping process that replace http:// links with https:// links all around the site, e.g. on the question itself. While indeed not bumping on its own, when something else bumped the question to the front page, the last modified by showing Community.
Can this please be fixed? Expect to see the actual last modifier in those cases.