When the number of tabs open exceeds a certain limit, the Firefox browser puts too many tabs that are not suitable in the Overflow Menu. If you have some extensions installed that hide the tab, Firefox displays a warning that some of the tabs are not visible and that users can access them through the overflow menu.
When you open too many tabs in your Firefox browser, the browser displays the “Lists All Tabs” button on the tab bar, allowing you to click the button to see and open some tabs that exist behind the scroll arrow. Firefox is the only browser with this feature, and Chrome does not offer it.
A message pops up whenever a user opens a new tab.
Access your hidden tabs. An extension… Some of your tabs are being hidden. You can access it via the V (List all tabs button).
This notification option provides options for Keep tabs hidden and Disable Extensions.
This warning is useful if an extension is installed without the user’s knowledge. But for those who do install such extensions, the notification is a bit annoying.
Firefox doesn’t provide a preference for hiding the Access Hidden Tabs dialog box, so you’ll need to click the Keep Tab Stab Hide option when you use the extension to turn off the reminder.