When admins hide edit's summaries from desktop version it still apparent from mobile version and this thing is very annoying because such edit's summaries contain inappropriate words and sometimes cursing. I wish this problem to be solved as early as possible. Regards.
The hidden edit summary is not visible to unprivileged users; it's visible to users who have permissions to view it, but there's no indication in the UI that it is hidden. In desktop pages, you need to click through to see hidden edit summaries even if you have permission to view them.
@1339861mzb has helpfully provided some images showing the issue.
Desktop - for a **hidden** revision a message is shown and it is not possible to see the diff OR the summary by default. A link is provided to view the diff and controls are shown to reveal the summary.
Mobile - for a **hidden** revision the diff is always shown and the edit summary is shown (potentially containing curse words and should be considered a form of harassment for editors)
Desktop - in history page the summary is treated differently visually (via a strikethrough) to signal a deleted revision.
Mobile - in history page the summary looks no different from other pages for admins so doesn't indicate it is hidden (nor does it provide mechanisms to hide):
(for [[ https://ar.m.wikipedia.org/w/index.php?title=%D8%AE%D8%A7%D8%B5:%D8%AA%D8%A7%D8%B1%D9%8A%D8%AE/%D9%85%D8%B3%D8%AA%D8%AE%D8%AF%D9%85:Helmoony&offset=20110811154907&uselang=en | non-admins ]] it is however surpressed:
[[ https://ar.m.wikipedia.org/w/index.php?title=%D8%AE%D8%A7%D8%B5:%D9%81%D8%B1%D9%82_%D8%A7%D9%84%D9%85%D8%AD%D9%85%D9%88%D9%84/13873739&uselang=en | the diff ]] is hidden but the edit summary still shows o_O:
= Developer notes
* We already have code in InlineDifferenceEngine to check isSuppressedDiff and isUserAllowedToSee but when user is allowed to see.
$allowed = $this->isUserAllowedToSee(); but SpecialMobileDiff does not utilise these in getIntroHTML - it renders summary regardless.
* MobileSpecialPageFeed::renderFeedItemHtml renders the rows in the history, contributions etc... It expects summary to be hidden before rendering.
* SpecialMobileContributions::showContributionsRow, SpecialHistory::showRow, SpecialHistory::showFeedResultRow all duplicate code for working out what the summary should be. If a user can see a deleted comment we render it, however instead of doing this we should check the value of unhide (providing an unhide option when ready)
= Open questions
 In mobile we should hide by default to admins, but what control should we use for revealing hidden comments?