If you click the star to bookmark the current tab then the new bookmark is created in the Unsorted folder. The blue highlight star gets an "Edit this bookmark" tooltip and if you click the star another time then you get the "Edit This Bookmark" dialog and can move the bookmark to another folder. The list icon next to it (tooltip: Show your bookmarks) is actually the drop marker of the star button and behaves as the Bookmarks Menu button (that also looked like a star) known from older Firefox versions.

• https://support.mozilla.org/kb/how-do-i-use-bookmarks

There might be an add-on to put Bookmark This Page back on the "new" bookmarks button menu, but until then, here are two other ways to get that dialog which you might find convenient:

• right-click the page > Bookmark This Page (except if you right-click a link, image, or form field)
• Ctrl+d