I don't read it like that. It's not about 7 days real time, it's about 7 days on which you use the app. Since you can use Safari without visiting the PWA's dom

I don't read it like that. It's not about 7 days real time, it's about 7 days on which you use the app. Since you can use Safari without visiting the PWA's domain, this feature can delete the data of a PWA which runs in Safari. Since you can't use a homescreened PWA without it visiting the associated domain, the data saved by the PWA's domain will never be deleted for homescreened applications. But data associated saved by other domains can still get deleted if you use the application for 7 days without it opening that domain.