The arrows are shown on first paint but get removed after that.
mw-collapsible-toggle has all: unset and that seems to remove the image as well.

New code from 05281ad7260985dc3e735216e6195a5f15c1afde / https://gerrit.wikimedia.org/r/c/mediawiki/core/+/929012

The width and height in mw-enhancedchanges-arrow-space gets unset as well.

Grouped and single items on Special:RecentChanges are no longer aligned under each other for the same reason (grouped get width reset, single not). I have no good idea about fixing this css.

It's due to selector specificity – .mw-enhancedchanges-arrow-space has the same specificity as .mw-collapsible-toggle, and the second one is loaded later, so .mw-enhancedchanges-arrow-space { display: inline-block; } gets overridden by .mw-collapsible-toggle { all: unset; }.

This can be fixed by making the selector more specific, e.g. replacing .mw-enhancedchanges-arrow-space with .mw-collapsible-toggle.mw-enhancedchanges-arrow-space. We do this a lot.

But if this broke, then the change might also break custom toggles on-wiki. I didn't think of that before, and I'm not sure how risky it is. We could consider reverting the change as well.

@Tacsipacsi Thoughts?

First of all: sorry!

It’s getting late for me, so I’d appreciate if someone unblocked the train by reverting my change. I don’t think it could break on-wiki styles (on-wiki styles are always loaded after software-defined ones, aren’t they?), but if it broke this software-defined style, it can potentially break other software-defined styles as well, so the solution needs careful thinking (for which I’m definitely not capable at 2AM).

Change 929968 had a related patch set uploaded (by Gergő Tisza; author: Gergő Tisza):

[mediawiki/core@master] Revert "jquery.makeCollapsible: Use `unset: all` on buttons"

https://gerrit.wikimedia.org/r/929968

Change 929969 had a related patch set uploaded (by Gergő Tisza; author: Gergő Tisza):

[mediawiki/core@wmf/1.41.0-wmf.13] Revert "jquery.makeCollapsible: Use `unset: all` on buttons"

https://gerrit.wikimedia.org/r/929969

Change 929969 merged by jenkins-bot:

[mediawiki/core@wmf/1.41.0-wmf.13] Revert "jquery.makeCollapsible: Use `unset: all` on buttons"

https://gerrit.wikimedia.org/r/929969

Mentioned in SAL (#wikimedia-operations) [2023-06-14T08:40:06Z] <tgr@deploy1002> Started scap: Backport for [[gerrit:929969|Revert "jquery.makeCollapsible: Use unset: all on buttons" (T333357 T338927)]]

Mentioned in SAL (#wikimedia-operations) [2023-06-14T08:41:51Z] <tgr@deploy1002> tgr: Backport for [[gerrit:929969|Revert "jquery.makeCollapsible: Use unset: all on buttons" (T333357 T338927)]] synced to the testservers: mwdebug1002.eqiad.wmnet, mwdebug1001.eqiad.wmnet, mwdebug2002.codfw.wmnet, mwdebug2001.codfw.wmnet

Mentioned in SAL (#wikimedia-operations) [2023-06-14T08:48:21Z] <tgr@deploy1002> Finished scap: Backport for [[gerrit:929969|Revert "jquery.makeCollapsible: Use unset: all on buttons" (T333357 T338927)]] (duration: 08m 14s)

Reverted on wmf.13 to unblock the train, I'll leave it to someone else whether the revert needs to be merged on master.

Change 929968 merged by jenkins-bot:

[mediawiki/core@master] Revert "jquery.makeCollapsible: Use `unset: all` on buttons"

https://gerrit.wikimedia.org/r/929968