Incorrect colours due to GDK colour management

Steps to reproduce

1. Run a GTK4 app

Current behavior

Incorrect colour rendering, as shown in the below screenshot of the "GNOME Application" template created by GNOME Builder:

Note the darkness of the window controls in the upper right.

Expected outcome

Correct colour rendering, as shown in this screenshot taken with GDK_DISABLE=color-mgmt:

Version information

Additional information

Through trial and error, I've found three environment variables which restore the correct behaviour:

• GSK_RENDERER=gl
• GDK_BACKEND=x11, although this breaks scaling
• GDK_DISABLE=color-mgmt

The difference is much more obvious with the app I'm working on:

Incorrect (default):

Correct:

The issue did not occur with Fedora 40.