I've lost localStorage on PWAs before. But that was a number of years ago when I was still bothering to develop them. I also lost data in appcache repeatedly,

I've lost localStorage on PWAs before. But that was a number of years ago when I was still bothering to develop them. I also lost data in appcache repeatedly, then service workers came along to fix that, because the browser vendors' strategy for broken implementations is to deprecate them with an even more complex standard that they will never finish. Then they can close your bugs against the old standard that they never finished implementing as WONTFIX and everyone gets a promotion for shipping.