Set value to 0
Go to options and uncheck "Open links in tabs instead of new windows"
Go to options and check "Open links in tabs instead of new windows"
You may be able to just set the value to "3" instead of zero, but since I am not sure what ...
There is no need for a script. Wikipedia gives you the option via a pop-up no matter the browser.
Even not logged in you can turn it off by:
Hover over any article link.
On the preview, click on the gear icon in the bottom-right corner.
Select "Disable" in the pop-up and then "Save".
The linked question now has an answer that works in Firefox (confirmed in 70 on Windows). Copyediting:
On Firefox [use] Alt + Up and Alt +
Down to [change] worksheet and avoid conflicts with [changing]
the browser tab.