[BUG] Switching users in OAuth2 auth flow ends with unsuccessful authorization

[jesmrec]

Steps to reproduce

1. Open OAuth2 server session
2. Open drawer -> manage accounts
3. Click on the key icon to edit the account auth info
4. Log In to start web authorization
5. Select Switch users
6. Enter correct credentials (same account as 1.)
7. Authorize

Actual behaviour

Unsuccessful authorization

device-2022-01-19-165647.mp4

Error is a 400 after requesting POST http://192.168.1.20:39000/index.php/apps/oauth2/api/v1/token:

{
    "error": "invalid_grant",
    "error_description": "code verifier invalid"
}

Expected behaviour

As the correct credentials, file list should be displayed instead of error

Nexus 6P Android7
Pixel2 Android11
HuaweiP20L Android9

[michaelstingl]

Known limitation, after oC10 OAuth 2.0 app learned PKCE with 5.0. See owncloud/oauth2#309

[jesmrec]

Expected behaviour then. Reopen if behaviour changes.