Hello
This behavior is due to the design of Microsoft Edge's kiosk mode. When you launch Edge in kiosk mode with the command you provided, it is intended to enhance control and management by restricting certain actions, such as opening new windows or tabs.
Here are a few things you can try to address this issue:
Check Kiosk Mode Settings: Ensure that your kiosk mode settings are configured correctly. You might want to look into the settings related to pop-ups and redirects. In the Edge settings menu, navigate to "Site permissions" and then "Pop-ups and redirects." Make sure the option to open sites in new tabs is toggled off.
Group Policy Settings: If you are managing Edge through Group Policy, check the policies related to kiosk mode. Unfortunately, there might not be a specific setting to force links to open in the same window, as kiosk mode is designed to limit navigation to a single window.
Kiosk Edge - Opening Links in a new window - Microsoft Q&A
Command Line Options: Review the command line options you are using. The --kiosk and --edge-kiosk-type=fullscreen options are correct for launching Edge in fullscreen kiosk mode, but there might be additional parameters or configurations needed to achieve the desired behavior.
MS Edge Kiosk Mode, Multi Tab Syntax for Command Line - Microsoft Q&A