不考虑在网页内设置订阅通知的情况，在图文消息中设置订阅通知，当微信用户同意或拒绝通知时，事件推送的没有包含来源的图文消息id，推送的xml数据如下：

<xml>
    <ToUserName><![CDATA[gh_123456789abc]]></ToUserName>
    <FromUserName><![CDATA[otFpruAK8D-E6EfStSYonYSBZ8_4]]></FromUserName>
    <CreateTime>1610969440</CreateTime>
    <MsgType><![CDATA[event]]></MsgType>
    <Event><![CDATA[subscribe_msg_popup_event]]></Event>
    <SubscribeMsgPopupEvent>
        <List>
            <TemplateId><![CDATA[VRR0UEO9VJOLs0MHlU0OilqX6MVFDwH3_3gz3Oc0NIc]]></TemplateId>
            <SubscribeStatusString><![CDATA[accept]]></SubscribeStatusString>
            <PopupScene>2</PopupScene>
        </List>
        <List>
            <TemplateId><![CDATA[9nLIlbOQZC5Y89AZteFEux3WCXRRRG5Wfzkpssu4bLI]]></TemplateId>
            <SubscribeStatusString><![CDATA[reject]]></SubscribeStatusString>
            <PopupScene>2</PopupScene>
        </List>
    </SubscribeMsgPopupEvent>
</xml>