iPhone Reddit remembers my log-ins

[Godspeed8230]

Hey,
so I have tried to figure out where Reddit saves my log-in information but I wasn't able to find it.
Here's what happens: Three years ago I created a reddit account. Then I deleted the app (not the account). I did not save it to my Passwords, KeyChain (I checked - there is nothing to be found).

Last week I re-downloaded the app and I was logged in with my old account. I tried deleting and re-installing it two more times and the app always remembers me, even after actively logging-out of my Reddit account. What the heck? How can I disable/delete this?
(Maybe deleting my account from Reddit would solve this but this is not the problem I am trying to solve here)

Thank you!

Edit: Additional details.

 

[Sheepish-Lord]

After you created the account, was it linked to your AppleID or Gmail account? Could be caching that and you should be able to unlink either in Apple settings or Google.

 

[Godspeed8230]

After you created the account, was it linked to your AppleID or Gmail account? Could be caching that and you should be able to unlink either in Apple settings or Google.

I just checked - no, there is no link to either AppleID or Gmail. It's so strange and alarming that Reddit has this deep connection to my iPhone. There has to be a place to unlink all of this.

 

[mystery hill]

If you have a Mac you can use the Keychain app to check if Reddit has saved a login to your iCloud account.

 

[Godspeed8230]

If you have a Mac you can use the Keychain app to check if Reddit has saved a login to your iCloud account.

Nope, I checked. No entries.

 

[arinamichel911]

Are you using any other third-party app that gets your account credentials?

 

[NoBoMac]

Could be iOS's convenience feature where an app developer/company can setup a group container to retain information, such as login ID, to make things smoother when going between their apps. Google and Microsoft, for example, saves this information so that you don't have to re-enter IDs when installing a new app from them: install and start using from the jump.

In the case of Reddit, not sure what their developer domain might be, or if they have multiple apps and if one of them is already installed so the group container will always be there, so will need to do some investigation. Quick scan of Wikipedia shows that the parent company of Conde Nast has a majority stake in Reddit, so a Warner Brothers app, Charter Comm, Conde Nast publication's app installed might be causing this, in addition to if the AMA app (still a thing, the app?) is installed along side main app.

Configuring App Groups | Apple Developer Documentation

Enable communication and data sharing between multiple installed apps created by the same developer.

developer.apple.com

Enable communication and data sharing between multiple installed apps created by the same developer.

An App Group allows multiple apps developed by the same team to access one or more shared containers. It also enables additional inter-process communication between those apps using Mach IPC, POSIX semaphores and shared memory, and UNIX domain sockets, among other IPC mechanisms. [...] Apps can belong to one or more App Groups. You can also use an App Group to share data between an app extension or App Clip and its host app.