Ticket for this issue probably exists, but was not able to discover it.

The most bug-ish part of it is perhaps that for the initial (creation) revision cases, the diff view is not a diff but page rendering.

Request was related for e.g. enwiki, cswiki …

In T423703#11833680, @taavi wrote:

Such changes to the title can be done by renaming the page. Using DISPLAYTITLE for the first character exists as MediaWiki considers all pages to start with an uppercase letter.

Possible partial workarounds (or quasi/pseudo workarounds) known to me:

@Bhsd Yes, I already did try the new (non-"legacy") version, as suggested before. The bug does not occur in it.

Looking at the previous dump 20251220.

Slight update: currently not being able to reproduce the bug in Arch Linux scenario (the same machine/system, not sure what's the "problem"),
but reproduced successfully in OpenBSD (the same machine/system), Firefox version 146.0.1 in both cases; also reproduced in Debian Trixie, Firefox 140.6.0esr.

These are currently not found (HTTP 404):

https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging1.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging2.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging3.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging4.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging5.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging6.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging7.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging8.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging9.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging10.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging11.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging12.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging13.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging14.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging15.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging16.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging17.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging18.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging19.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging20.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging21.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging22.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging23.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging24.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging25.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging26.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-pages-logging27.xml.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-all-titles.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-all-titles-in-ns0.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-siteinfo2-namespacesv2.json.gz
https://dumps.wikimedia.org/enwiki/20260101/enwiki-20260101-siteinfo-namespaces.json.gz

The second example (Crayon … png) unfortunately seem to may have incorrect colors in the original already?
UPDATE: Changed to different one ("Xterm" … png)

related: T178175: {{#time}} parser function should not accept dates with zero in day or month positions

In T178175#6566633, @Rwendland wrote:

This is the documented behaviour, so is correct. …

In T321989#8365615, @RoyZuo wrote:

…
and the problem is not limited to February. on the 31st day of any month, for all the months without the 31st day, this error will occur.
…

I see style

btw, anchors were not mentioned yet, subject of T407884: Vector 2022's sticky header toolbar overlaps beginning of a content linked with an achor (~duplicate issue)

@A_smart_kitten Right, it seems to be describing essentially the same problem. I did not see that one. I would not be against merging.

.. just a note on linking to CodeMirror 5 (legacy): current enwiki production version is 6.0.0, having the bug (too)

@A_smart_kitten

… if disabling subpages in the Talk: namespace is also wanted, please could I ask that it's proposed specifically in an onwiki discussion?

It seems to behave same way for

• enwiki {{Anchor|…}} template (example, w/safemode)
• raw HTML anchor <span class="anchor" id="…"></span> (corresponding to the template output) (example, w/safemode)
• the same with no class, <span id="…"></span> (example, w/safemode)

In some cases, it seems that during the toolbar appearance, page is scrolled correctly anyway. (And, precisely. Unlike as for section links, where a couple of lines above the section header from the previous section are visible too.)
Not sure what exact conditions are needed, but it happens during the same browsing session with the same link, in minor amount of cases.
Btw, I almost always do open these links in a new tab (Ctrl+click).

This has been bugging me for some time (months or years) already. Took me some amount of testing to realize it's a Vector 2022 skin issue for logged in user only. (Initially I wanted to report scrolled-out beginning of anchor links, generally.)

@Tacsipacsi (, @matmarex ) I think that an issue of post signature dates unrecognized (discussion tools timestamp link not made) is unrelated to some invitation banners (not widely known feature).

The were (≥ 10 years ago) concepts to introduce subpages for Czech Wiktionary entries (e.g. here). Never adopted.

Additional remarks: For me it is debatable if it is bug. But it feels so, if trailing period is not considered a part of URL (despite "." being URI uric unreserved character like "-", "_"), but typographic (closing) quote is included.