It appears that Microsoft is indeed using a phased rollout strategy for the Windows 11, version 25H2 update. Even if your system has been successfully upgraded, the feature update may not immediately appear in the Windows Update list for all users. This gradual rollout means that it can take some time before the update is available to all eligible devices, and it may only show up in the Feature updates list after it has been fully rolled out to your specific device.
If you are not seeing the update listed, it is likely that you may need to wait for it to become available in your region or for your specific device configuration. Additionally, subsequent cumulative updates may also play a role in making the version visible in the update list.
For immediate assistance with Windows update issues, you can check the Microsoft support resources.