Sharepoint PowerBI embedded / External User Figuring Out the Direct Link of the Workspace

Background

We have set up a Sharepoint site, PowerBI workspace and Office 365 group with external users. The goal is to use the Sharepoint site as a platform to share PowerBI reports with external users. The PowerBI web part is used to embed the report to the page. I add an external user to the O365 group so he/she can view the Sharepoint page with an embedded PowerBI report. O365 group is also added to the PowerBI workspace with Viewer access. My PowerBI workspace has several reports which I don't want the external users to see them all. I manage the access from the Sharepoint page. If a user can see the page, he can see the report. 

An external user with a PowerBI Pro license can go to app.powerbi.com, and he cannot see my workspace and any of the reports. 

https://ibb.co/VxW70Wb 

Issue and Question

As an external user, when I go and click on the "View the Page Source" from the browser, I am able to view the embed link. The embed link and page source can be used to construct the Direct Link to the PowerBI report. 

https://app.powerbi.com/groups/-----------groupid------------------/reports/------reportid----------------------?---------tenantid------------------------

If the external user uses the link constructed above, he starts seeing the link to my workspace with all the reports which leads him to view all my reports under the workspace. 

https://ibb.co/9tPYm9J 

any thoughts on preventing that?