Often these web apps, just doesn't work on iOS. Seen that happen quite a few times. Also keep in mind Safari on iOS has 7-Day Cap on All Script-Writeable Storages such as:
Indexed DB
LocalStorage
Media keys
SessionStorage
Service Worker registrations and cache
Unless if the Web Applications was added to the Home Screen.
Indexed DB LocalStorage Media keys SessionStorage Service Worker registrations and cache
Unless if the Web Applications was added to the Home Screen.
https://web.dev/storage-for-the-web/