Creating/updating change notification subscriptions does not return the expected ExpirationDateTime value

Question

When creating or patching a change notification subscription using the .NET MS graph SDK, the ExpirationDateTime is not set to the expected value. I am creating a subscription using the code from https://learn.microsoft.com/en-us/graph/change-notifications-delivery-webhooks?tabs=csharp#subscription-request. I set my ExpirationDateTime value as a DateTimeOffset for 10065 minutes from creation (which should be acceptable for messages according to https://learn.microsoft.com/en-us/graph/api/resources/subscription?view=graph-rest-1.0#subscription-lifetime) and pass it into a new Subscription object. When the request is completed and the subscription object is returned, the ExpirationDateTime does not represent the value I'm setting. It's usually only a day in advance when I would expect it to be around 6 days from creation. The same issue occurs when updating subscriptions using the code from https://learn.microsoft.com/en-us/graph/api/subscription-update?view=graph-rest-1.0&tabs=csharp#request. I have also tried to pass in the ExpirationDateTime as an AdditionalData parameter (suggested in https://github.com/microsoftgraph/msgraph-sdk-dotnet/issues/2269) and the issue persists.