Android's WebView can use local storage, service workers, IndexedDB and many other features. However I have not been able to find any information regarding where this data is stored and when it is be cleared out.
With some tests I've been able to determine that they are not stored in the cache (since I can delete the cache and localStorage and IndexedDb still have the old values).
Exploring the filesystem I've been able to find two places where this data could be stored:
/data/data/<app-name>/app_webview/Default/
/data/user/0/<app-name>/app_webview/Default/
These folders contain the folders IndexedDb, localStorage, Service Worker.
Picture of the folder containing the data
The main question I have is who handles this data and when/why will it be deleted?