Apple's Intelligent Tracking Prevention (ITP) and Safari moves to a 7-day cap on all script-writeable storage as a result of workarounds the previous cap.

Now ITP has aligned the remaining script-writable storage forms with the existing client-side cookie restriction, deleting all of a website’s script-writable storage after seven days of Safari use without user interaction on the site. These are the script-writable storage forms affected (excluding some legacy website data types):

Indexed DB

LocalStorage

Media keys

SessionStorage

Service Worker registrations

[webkit.org...]