Nextcloud: User files is disclosed when someone called while the screen is locked

Summary:

User files in the server is disclosed while the screen is locked when someone called.

Steps To Reproduce:

[add details for how we can reproduce the issue]

1.) Make 2 Accounts, Lets call them Account A and Account B
2.) Using Account A login to (https://nextcloud/apps/spreed/)
3.) Using Account B login to NextCloud Talk App in your Phone and Lock the Screen
4.) Using Account A call Account B
5.) Using Account B accept the call and click the Message or SMS icon in the bottom left
6.) Attach a file and Press share from your nextcloud server
7.) You can see the user files

Supporting Material/References:

[list any additional material (e.g. screenshots, logs, etc.)]

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Impact

A malicious attacker can see the user files by calling the phone while the screen is locked.