Jan 07 2020 06:47 AM
I'd try reaching out to subject matter experts in dedicated forum over here.
https://techcommunity.microsoft.com/t5/office-365-calendar/bd-p/office365_calendar
Jan 07 2020 09:00 AM
Most likely someone toggled the AddNewRequestsTentatively/TentativePendingApproval flag, check the values.