This is not unique to Rani, at least if you have “session restore” enabled in the System Settings. If you had Rani open when you shut down your computer, the “open in last session” feature will restart the program automatically at login. This is not a bug, it is a feature, (if session restore is enabled).
Simply exclude Rani from automatically being restarted in System Settings.
Hope that’s your issue, as it’s easily corrected if it’s the session restore feature responsible for this.