After all these years, Mozilla have finally decided to offer an option to disable tab detach.
https://techdows.com/2020/01/disable-tabs-tearing-or-tab-detaching-in-firefox.html

I found discussions regarding this "tear-off tabs" issue going back several years. Firefox should have the ability to disable tear-off tabs already built-in to the settings. This solves the problem! Thank you for making this extension!

This need to all browsers!

This is my favorite addon now.

Love it.

Seems like Tab detach has been annoying people for a few years. This just started to happen to me the past few months. So happy to have this add on to disable this horrible feature.

This add-on is great but when i use the "Move to new Window" it shouldn't move it back. Only if i drag the tab it shoudl move it back. Now it is impossible to move a tab to a new window even if i want to do it. It seems that someone already have found a solution by releasing "Disable Tab Detach 2" :)

Thank you for a great solution to a nagging problem. I have one question. Why does this extension add a line to the page actions (3-dot) menu?

This is faster/lighter than its only "rival", DTD2, but it also undoes moving to a new window via right click, and moving to an existing window via drag-and-drop. I am used to working with multiple windows, which means I need to move tabs from one another often, and this is the reason I cannot use this add-on. All that being said, I cannot give this less than three starts, because it does what it says and it is lightweight.

Thank you for providing that!

The plugin works flawless and does what it should.

Disable Tab Detach 2 works with pinned tabs and also has an on/off button.

https://addons.mozilla.org/en-US/firefox/addon/disable-tab-detach-2/