The Bookmarks button may have been dumped in the Customize Palette during the update.

https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars

Use the Restore Default Set button at the bottom-right corner of the Customize Palette.

I don't know what the Customize Palette is but if it is the right-click menu of the Bookmarks toolbar all that has on it is :

                           Open in all tabs
                           New bookmark...
                           New folder
                           New separator

                           Cut
                           Copy
                           Paste
                           Delete

                           Sort by names

                           Properties

That's all it shows.

The Bookmarks Toolbar is giving you "context" items for the Bookmarks.

Right-click in a blank spot on the Navigation toolbar or the Tabstrip.