[Bug]: Manual Color Theming Breaks Icons

[tpglitch]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

In the latest version of Nextcloud 32, if you go to Theming admin settings and set a custom color for primary & secondary, eg FF3568, all topbar icons will become black.

Steps to reproduce

1. Visit /settings/admin/theming
2. Set both primary and secondary color to FF3568 (tested with that mainly)
3. Observe issue

Expected behavior

Icons obey and adapt to color modification

Nextcloud Server version

32

Operating system

Other

PHP engine version

PHP 8.4

Web server

Apache (supported)

Database engine version

MariaDB

Is this bug present after an update or on a fresh install?

Upgraded to a MAJOR version (ex. 31 to 32)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

I have to go through an extensive process that get SSH access to the server, but if the issue is found to be linked to the config somehow I can request it.

List of activated Apps

Same for this, but also was tested in a fresh install

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Literally empty. No warnings or errors.

Additional info

No response

[tpglitch]

Also it appears to be specifically caused by changing the background color, not primary.

[tpglitch]

Bump