@Joachim Berghmans, Thanks for posting in Q&A.
For the key "enforcedSoftwareUpdateDelay", it is used to delay visibility of updates to end users. For more details we can see in the following link:
Correctly, the feature is still there which you configured in device restriction. But this setting is used to hide an update from device users for a period of time on your supervised iOS/iPadOS devices. A restriction period can give you time to test an update before it's visible to users to install. After the device restriction period expires, the update becomes visible to users. Users can then choose to install it, or your Software update policies might automatically install it soon after.
For the software update download and install, it is controlled by iOS update policy with the setting "Schedule type". Software update policies install updates based on their own schedule, regardless of the update being hidden or visible to the device user.
For our situation, you can check what we configured the "Schedule type" and if the policy is applied to the device. Also see if the device is available during the scheduled time.
Hope it can help.
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