It used to. They have largely changed that now - all data is deleted once the last app from a given vendor has been deleted (though it's not instant, and seems to apply weirdly on TestFlight + ad-hoc builds)
I delete Facebook a few times and every time I installed the app the first screen I got prompted with was "Hello Josh, would you like to sign in with your stored details?" Not all data is scrubbed. This persisted to even today running on iOS 17 Public Beta.
I have experienced the same thing. Even when Apple made changes in Keychain policy to try to combat fingerprinting, “I never got the memo.” That sounds nuts, but I’m in the same boat.
I’ve had a few apps I’ve redownloaded months later, the only one from the developer, and my auth state was preserved.
I keep hearing that the Keychain data should be deleted, but my iCloud Keychain is filled with long-dead data
Everything in this space is so muddled. Deleting the last app from a vendor should erase that data. On the other hand, if you restore your phone from another device, that should never require relogging into anything.
Yeah, last I checked, encrypted itunes backups would keep the "this device only" keychain data. Which would only work when restored to the same device - it needs the UID key from the secure enclave to decode. (I wrote code a few years ago to decrypt the rest of the keychain.)
At one point, google authenticator started marking its entries as "this device only". I don't know if they've backed off on that since then.
