Hi, you can submit this idea to https://connect.mozilla.org/ . Here's support only.

Please give update to ask password to open Incognito tab and view Incognito tab.

Hi,

The people who answer questions here, for the most part, are other users volunteering their time (like me), not Mozilla employees or developers. If you want to leave feedback for developers, you can go to the Firefox Help menu and select either Share ideas and feedback… or Submit feedback…, depending on your Firefox version. Alternatively, you can use this link. Your feedback gets collected by a team of people who read it and gather data about the most common issues.

You can also file a bug report or feature request. See File a bug report or feature request for Mozilla products for details.