Hi @Young, Gershon,
Welcome to the Microsoft Q&A Platform!
We are aware of the Apple's Push Notification Service (APNS) server, you do not need to worry about this. Azure Notification Hubs will handle it for you, Microsoft keeps these certificates updated, so you can continue using our service without any interruption.
Regarding your end, if you are using a self-owned APNS certificate instead of the managed one offered by Notification Hubs, you might need to update your certificate. If you are using the default certificate that we manage, you do not have to do anything.
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