Firefox seemingly very recently shipped their own titlebar controls buttons, which worsens even further the lackluster OS integration. In the screenshot you see my regular control buttons on the window to the left (default KDE Plasma theme) and the new custom buttons Firefox is serving now.
Would anyone know how to undo that change in about:config or anywhere else?
Right click on the toolbar and click "Customize Toolbar" and in the bottom left there should be a tick box to turn it back to normal
Thank you for replying, but that just adds a standalone titlebar with just a title and the controls, while moving all the other functions like the address input to a regular toolbar, as the options suggests. I’d like to keep all the functions and the titlebar controls in one single titlebar, but with the OS control buttons, as it used to be before the last Firefox update.
That's the only way I know of, good luck finding a solution for you