Update@2017-10-31: The situation does not seem to be an issue anymore; see the answer in the linked question below for more information.
Based on the information you provided this seems to be a known issue that was already reported; we are tracking the issue in our backlog, but at this time I can’t provide you with a definitive timeline for when it will be addressed. The previous report is this one: Calling user info endpoint returns stale information for email verified attribute.
In terms of workaround, if you’re able to perform a call to a back-end/API that you own and then from that back-end/API perform a Management API call to retrieve the user information then you should be able to obtain up-to-date information about the email verification state. The reason you should proxy this call through your own back-end/API is that the process to obtain a token to call the Management API is not suitable for browser-based applications.