Thanks for your reply, but I was just trying to avoid this.
Looks like this is the only way to get it working again.

Hello,
As I wrote in the first message, the defragmentation is not working.

Hello and thanks for your reply.
I'm really frustrated about this and very shocked about Microsoft's support.
They have closed the ticket without telling me about this setting.

Anyway, I have changed these settings in Azure AD, but the Guest users can still see the full AD info about corporate users.
Incredibly, no one reported this to Microsoft.
This disclosure is illegal in EU due to the GDPR compliance.
You can't expose personal information about corporate users without any warning and by default, these settings should be private.

Hello and thanks for your reply.
I'm really frustrated about this and very shocked about Microsoft's support.
They have closed the ticket without telling me about this setting.

Anyway, I have changed these settings in Azure AD, but the Guest users can still see the full AD info about corporate users.
Incredibly, no one reported this to Microsoft.
This disclosure is illegal in EU due to the GDPR compliance.
You can't expose personal information about corporate users without any warning and by default, these settings should be private.