Would a suitable approach be to add an exception for skin-invert and skin-invert-image in content.media-dark.less?

/* Desktop legacy HTML */
.mw-parser-output,
/* Parsoid HTML (mobile) */
section .mw-heading ~ div,
/* Parsoid HTML (desktop) */
section,
/* e.g. https://en.wikipedia.org/wiki/Pullback_(category_theory)#Universal_property */
dd,
/* For targeting p span.mw-default-size */
p {
	> span.mw-default-size,
	> figure[ typeof='mw:File' ],
	> figure[ typeof='mw:File/Thumb' ],
	> figure[ typeof='mw:File/Frameless' ] {
		&:not( .skin-invert, .skin-invert-image ) {
			img {
				background-color: @background-color-base-fixed;
				color: @color-base-fixed;
				filter: brightness( 0.8 );
			}
		}
	}
}

Change #1153417 had a related patch set uploaded (by Gerrit Patch Uploader; author: My Name):

[mediawiki/core@master] skip dark-mode-image-styles rules for elements of class skin-invert-image, requested in T391800

https://gerrit.wikimedia.org/r/1153417

The patch relocates some comments.

This has not been done arbitrarily, but stems from the observation
that a less to css preprocessor generates an empty rule, if the first
line consists solely of a comment:

html.skin-theme-clientpref-night {
  /* Desktop legacy HTML */
}

The difference can be tested online,
for instance with less-preview

Change #1153417 had a related patch set uploaded (by Jdlrobson; author: My Name):

[mediawiki/core@master] skip dark-mode-image-styles rules for elements of class skin-invert-image

https://gerrit.wikimedia.org/r/1153417

Change #1153417 merged by jenkins-bot:

[mediawiki/core@master] Skin: skip brightness filter for images with skin-invert-image class

https://gerrit.wikimedia.org/r/1153417

Test Result - Prod

Status: ❓
Environment: dewiki
OS: macOS Sequoia 15.5
Browser: Chrome Canary (latest as of test date)
Device: MS
Emulated Device: NA

Test Steps

Test Case 1: Inverted image displays correctly in dark mode

1. Visit https://de.wikipedia.org/wiki/Jiu_Jitsu
2. Switch to dark mode
3. Locate the first image in the article (kanji image)
4. ❓ AC1: Confirm that the image is visually inverted using skin-invert-image styling (e.g., appears white on black)

The what should happen section states that the colors should be inverted. That's not what happens, and I'm not sure it is what should happen. Instead, the white bacground of the image goes from ffffff to d2d2d2 which is subtle, but probably what it should do.

Light	Dark

1.45.0-wmf.5 isn't live on dewiki yet