STR:

1. Using Dolphin connect to (bookmarked here) sftp://user@host:port/path
2. Close Dolphin
3. Wait for long enough (minutes, hour)
4. `ss -tuapn`

EXPECTED:

No TCP connection to the remote host.

ACTUAL:

Even 1 hour later ss shows a connection to the remote host with state ESTAB,
corresponding to process users:(("sftp.so",pid=11305,fd=8)).

Additional note:

The remote host is configured to automatically drop login session if there is
no activity for 30 minutes but it doesn't seem to prevent connection
persistence.

Setting severity to Major because this has security and privacy implications.