EWS api GetItem (mail) response ErrorInvalidUserPrincipalName but principal name is same as Graph api response

Question

I used EWS api GetItem to get mail message item, but for certain users, server response ErrorInvalidUserPrincipalName (other users are work without errors), and I check principal name is correct with Microsoft Graph api.

<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages">
<soap:Header>
<t:RequestServerVersion Version="Exchange2013"/>
<t:ExchangeImpersonation>
<t:ConnectingSID>
<t:PrincipalName>xxx@X .com</t:PrincipalName>
</t:ConnectingSID>
</t:ExchangeImpersonation>
</soap:Header>
<soap:Body>
<m:GetItem>
<m:ItemShape>
<t:BaseShape>IdOnly</t:BaseShape>
<t:IncludeMimeContent>true</t:IncludeMimeContent>
</m:ItemShape>
<m:ItemIds>
<t:ItemId Id="xxx"/>
</m:ItemIds>
</m:GetItem>
</soap:Body>
</soap:Envelope>

And server response ErrorInvalidUserPrincipalName.

<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Body>
<s:Fault>
<faultcode xmlns:a="http://schemas.microsoft.com/exchange/services/2006/types">a:ErrorInvalidUserPrincipalName</faultcode>
<faultstring xml:lang="en-US">The impersonation principal name is invalid.</faultstring>
<detail>
<e:ResponseCode xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">ErrorInvalidUserPrincipalName</e:ResponseCode>
<e:Message xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">The impersonation principal name is invalid.</e:Message>
</detail>
</s:Fault>
</s:Body>
</s:Envelope>

I used Microsoft Graph user api (GET /users/{id | userPrincipalName}) to check principal name, the principal name is same as I bring in EWS GetItem request but still get ErrorInvalidUserPrincipalName response.

{
"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users/$entity",
"id": "zzz",
"businessPhones": [],
"displayName": "yyy",
"mail": "xxx@X .com",
"userPrincipalName": "xxx@X .com"
...
}

I tried to send same EWS GetItem with PrimarySmtpAddress tag rather than PrincipalName (smtp address is same as principal name), and it works without error, I don't know why use PrincipalName will get ErrorInvalidUserPrincipalName response even principal name looks correct.

<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages">
<soap:Header>
<t:RequestServerVersion Version="Exchange2013"/>
<t:ExchangeImpersonation>
<t:ConnectingSID>
<t:PrimarySmtpAddress>xxx@X .com</t:PrimarySmtpAddress>
</t:ConnectingSID>
</t:ExchangeImpersonation>
</soap:Header>
<soap:Body>
<m:GetItem>
<m:ItemShape>
<t:BaseShape>IdOnly</t:BaseShape>
<t:IncludeMimeContent>true</t:IncludeMimeContent>
</m:ItemShape>
<m:ItemIds>
<t:ItemId Id="xxx"/>
</m:ItemIds>
</m:GetItem>
</soap:Body>
</soap:Envelope>

And I use PowerShell command (Get-Mailbox | Select-Object -ExpandProperty UserPrincipalName) to check PrincipalName on Exchange, and found the PrincipalName is different to Graph user api response, the PrincipalName on Exchange server and Graph's response is auto sync or not? Why they are different?
And which tag (PrimarySmtpAddress or PrincipalName) should I use to send EWS GetItem request?

Thanks!