By when SAP would share details of 1H 2023 release with list of new items including -
mandatory, admin opt-in / admin opt-out deliveries of the release items?
This information is usually available in "What's New Viewer", you need to wait more near of Release to be deliver in Preview tenant to have this info available for you to check.
In this way, keep an eye on Release page, available here in Successfactors Community to understand when the full list of features will be available.
Then this list is updated every Friday. To see what was last updated, you need to go to the columns and select "show" to "Latest Document Revision".
Will Testing be down after June 2nd? I came across this but it's for Production
SAP SuccessFactors HXM Core (EV19341715)
Notification Sent: 02/08/2023 23:11
Event Type: Maintenance
Start Time: 06/02/2023 23:00
Duration: 07 Hours 00 Minutes
Maintenance Expected End Time: 06/03/2023 06:00
Impact: You will not have access to Employee Central production environment during the scheduled release deployment window.