Failed to list all calendars for certain users with graph api

We failed to list all calendars for certain users with graph api, only 2 calendars are listed. However, when we use ews api, we can list all 7 calendars with FolderClass being IPF.Appointment. Does anyone know why this inconsistency between both apis?

graph api endpoint:

https://graph.microsoft.com/v1.0/users/8057cafb-1848-4b5d-a213-5dc40453c8f7/calendarGroups/{calendar_group_id}/calendars

ews api endpoint:
https://outlook.office365.com/EWS/Exchange.asmx

<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages"
    xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"
    xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
    <soap:Header>
        <t:RequestServerVersion Version="Exchange2013" />
        <t:ExchangeImpersonation>
            <t:ConnectingSID>
                <t:PrincipalName>user principal name</t:PrincipalName>
            </t:ConnectingSID>
        </t:ExchangeImpersonation>
    </soap:Header>
    <soap:Body>
        <m:SyncFolderHierarchy>
            <m:FolderShape>
                <t:BaseShape>IdOnly</t:BaseShape>
                <t:AdditionalProperties>
                    <t:FieldURI FieldURI="folder:ParentFolderId"></t:FieldURI>
                    <t:FieldURI FieldURI="folder:DisplayName"></t:FieldURI>
                    <t:FieldURI FieldURI="folder:FolderClass"></t:FieldURI>
                </t:AdditionalProperties>
            </m:FolderShape>
        </m:SyncFolderHierarchy>
    </soap:Body>
</soap:Envelope>