Backspace Enabler 作者： Mikko Hämäläinen

Mozilla Firefox has long offered the ability to hit the Backspace key to go back to the previous page. However, that changes with Firefox 86 when the company has disabled the feature by default.
Backspace Enabler Mozilla Add-on is used to enable the backspace key to act as a shortcut for the browser's back button. Pressing the Backspace key will go back a page in Firefox.
The delete text functionality for Backspace key is retained and active while your cursor is on any text field.
Please post in review any issues you experience, or just simply "It's working".

Keep in mind it will work only if you have something to go back to.