This post explains the reason for prompting for entering the password of Apple ID when updating the apps.
Issue Description
It keeps prompting for entering the password of Apple ID when the apps need to be updated on the iOS devices.
Cause
Firstly, an iOS device restriction policy was applied to the devices, which requires for entering Apple ID password for each app download. Please see the
screenshot below for the detailed settings about this policy.
Basically, this policy doesn’t enforce Apple ID password when updating apps. However, since from iOS 13, the function of Apple API changes, which causes
the change of behavior.

Workarounds
In the Intune portal, please navigate to
Device configuration – Profiles, choose and edit the profile, and disable the setting “Require iTunes Store password for all purchases”.
Please note that disabling the option will not have much impact on end users. They still can install apps on the iOS devices. The only difference is there
will not be any Apple ID password prompt anymore if the app has been purchased already.

References
iOS and iPadOS device settings to allow or restrict features using Intune
https://docs.microsoft.com/en-us/intune/configuration/device-restrictions-ios#app-store-doc-viewing-gaming
Hope the above information can be helpful. If you need further assistance on this issue, feel free to post a question via clicking "Ask a question" at the top left of this page,
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