Private callendar issue

Hi,

I have the following issue.

Private calendar Appointments of a shared or with full access permissions mailbox can be viewed.With REST (not MAPI) protocol.

Calendar is added to outlook via shared calendar.

"delegate can see private items" at delegate is not setup.

Enable shared calendar enhancement is active in microsoft 365 features in outlook account settings. (for REST) not "optimal" from data protection.

is there any info about the problem?

Thanks in advance and i appreciate ur feedback-suggestion.