My app is an inventory control system used by businesses that build electronics (https://partsbox.com/). Deleting client-side data after 7 days is ridiculous. You can't assume that people will always log in every week, in small businesses or design/manufacturing companies there are times when 2-3 weeks can pass without building new hardware or touching inventory.
Some web apps already saw the danger of having an easily purge-able storage on the client side and simply implemented an export function for their tools. I admire those tools more than the ones who overuse local storage for everything.
One such tool is draw.io, a flowchart maker. You use the app, persist everything in local storage and when you are done, you export your project into a file, all happening on the client side. When you need to edit, you import the file on launch. It's portable, it's protected from browser bugs/decisions and imho pretty user (privacy) friendly.
If you put data in IDB, it will stay there for 7 days and then if it gets deleted the delta sync would just download it again.