One more reason why Safari sucks for web developers:
It deletes all local site data if the site wasn't used for 7 days.

I guess it could have been relevant back when cross-origin talk was allowed in Safari at all. It is not anymore. But the behavior is still here.

If you've made a web To-Do app that uses localStorage/IndexedDB/..., your user creates a list in there, and 8 days later it's all gone — that's the reason.

And it is not part of standardized behavior, you have to know about this quirk and use one of the methods to ask the user to persist the data. Or create an auth system and store everything on server.

https://webkit.org/blog/10218/full-third-party-cookie-blocking-and-more/

Safari is the modern IE.