Change #1225127 had a related patch set uploaded (by Chlod Alejandro; author: Chlod Alejandro):

[operations/mediawiki-config@master] enwiki: change to 25th anniversary logo

https://gerrit.wikimedia.org/r/1225127

I've prepared the patch and scheduled it for deployment at the January 14 UTC late backport window. This window is 3 hours before January 15 00:00 UTC, but being a bit early shouldn't be that big of a problem.

Here are the logo tests based on the local deploy for Vector 2022, Vector Legacy, and Minerva.:

Vector 2022	Vector 2022 (dark)	Vector Legacy	Minerva	Minerva (dark)

Note that there's a CSS change required for MediaWiki:Vector.css to remove the logo while also preserving proper margins:

.skin-vector-2022 .mw-logo-icon {
    display: none;
}
.skin-vector-2022 .mw-logo {
    margin: 6px 0 6px 25px;
}

This does cause around 13.44 kB of wasted data due to the unused logo being loaded in anyway, but this file is part of /static and is cached hard.

Monobook looks the same as Vector Legacy. Modern and Cologne Blue do not have support for logos; English Wikipedia interface admins will have to apply the CSS hacks provided by sapphaline in that discussion to include the WP25 logos on those skins.

Timeless currently has an odd bug that's apparently still extant on the current version, where it doesn't support the high-DPI logos at $wgLogos despite documentation saying otherwise. You can see it on English Wikipedia right now. As a result, it's still using the blurry 100px Wikipedia globe logo (the site icon) which I've left unchanged. The related task is at T279645: Wikipedia logo is blurry in Timeless, icon config lacking 2x or svg variant, and has been open for a few years now. (see below)

Timeless situation is fixed. I ended up changing $wgLogos['icon'] anyway. Also added the CSS required to hide the logo on Vector 2022 to the comment above. See below for Timeless preview.

Change #1225127 merged by jenkins-bot:

[operations/mediawiki-config@master] enwiki: change to Wikipedia 25 logo

https://gerrit.wikimedia.org/r/1225127

Mentioned in SAL (#wikimedia-operations) [2026-01-14T21:06:55Z] <zabe@deploy2002> Started scap sync-world: Backport for [[gerrit:1225127|enwiki: change to Wikipedia 25 logo (T414271)]], [[gerrit:1225285|zhwiki: Temporary Logo Change for WP25 (T414299)]]

Mentioned in SAL (#wikimedia-operations) [2026-01-14T21:09:11Z] <zabe@deploy2002> chlod, zhaofjx, zabe: Backport for [[gerrit:1225127|enwiki: change to Wikipedia 25 logo (T414271)]], [[gerrit:1225285|zhwiki: Temporary Logo Change for WP25 (T414299)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.

Mentioned in SAL (#wikimedia-operations) [2026-01-14T21:15:58Z] <zabe@deploy2002> Finished scap sync-world: Backport for [[gerrit:1225127|enwiki: change to Wikipedia 25 logo (T414271)]], [[gerrit:1225285|zhwiki: Temporary Logo Change for WP25 (T414299)]] (duration: 09m 03s)