I have a homepage with an iframe containing my app LocalStorage, but when opening my app page the LocalStorage is lost.
structuration of the page: homepage : domain.com iframe and app : app.domain.com the localstorage is set up directly within the iframe and postmessage between iframe and parent works.
We see in the parent page that the LocalStorage for the sub-domain is set but opening the sub-domain on a new window it disappears :
The problem is detected On Safari 18 only.