Cannot create a read-only calendar with Microsoft Graph API

Using the following code

var calendarToCreate = new Calendar
{
   Name = "My read-only calendar",
   CanEdit = false,
   IsRemovable = false,
};

await graphClient
   .Users["my@email.com"]
   .Calendars
   .Request()
   .AddAsync(calendarToCreate);

the created calendar has `CanEdit` and `IsRemovable` both set to `true` instead of `false`.

What am I doing wrong?