Memory may be purged when app is backgrounded

To prevent NSCache from purging its memory when an app is backgrounded, one must use `NSDiscardableContent`

No file or test is named. Start by locating the NSCache usage and reviewing how its memory behaves when the app is backgrounded; check the NSDiscardableContent documentation and current cache implementation. Done means the relevant cached memory is not purged during backgrounding, with a regression test or reproducible verification where the repository supports it.

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