Firefox 72.0.2 Update. Firefox 74 will introduce the option to prevent tab detachment.

Available A maintenance release of Firefox 72.0.2, which addresses several stability issues:

• Fixed error, which caused issues opening downloaded files containing spaces in their filenames;
• Resolved hanging when opening the about:logins page with a master password set;
• Addressed issue compatibility issues with the implementation of CSS Shadow Parts added in Firefox 72;
• Corrected issues low performance in 1080p video playback at full screen.

Additionally, note the implementation in Firefox nightlies, on which the Firefox 74 release will be based, for the 'browser.tabs.allowTabDetach' setting (in about:config), which prevents tabs from detaching into new windows. Accidental tab detachment has been one of the most annoying shortcomings of Firefox, the resolution of which has been sought for 9 years. The browser allows you to drag a tab into a new window, but under certain circumstances, the tab detaches into a separate window when the mouse is moved awkwardly during a click on the tab. To avoid such behavior, extensions like Disable Tab Detach 2.

Source: opennet.ru