Hi kat291, the second button (<img src="https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/gallery/images/2021-06-19-21-15-40-ba2c56.png">) is optional and you can re-add it using the Customize panel. This article will get you in there: [[Customize Firefox controls, buttons and toolbars]]. Now, why did it disappear, that is harder to say. Did your Firefox mention doing a Refresh, Reset, or Tune-up recently or during your last update? That would go back to the initial default toolbar layout, and move all your customization files to your Windows desktop inside an Old Firefox Data folder. Do you see that folder? (If so, please hang onto it in case you notice other things missing.)