Hi @Ludwig_V thank you for raising this!
Project icon color is a per-user customization in Asana, meaning each user can set and view colors in a way that works best for them. Because of this, when testing with API tokens tied to different users, getting different color value responses is expected.
I understand how this can feel counter-intuitive, especially since the UI now includes a “Set for everyone” option that overrides individual settings. We’re aware this creates some confusion, and there’s active work underway to make color management more consistent between the UI and API, and to better align with user expectations.
Your feedback is valuable for us in shaping that experience, I’ll make sure it’s communicated.