With the version Firefox 109 release, you added this new button without the option to change its position or move into the overflow area. Please let use move it. I can remove/hide almost every other UI element in the browser, why not this?
This extension button is a downgrade from the overflow menu in every way - I can't move it, it's WAY too big for what it actually does, and it lists every single extension that I've got installed, despite most of them not needing any form of interaction at all. Let me hide extensions from this list, reduce the size of the extension window, and let me move it around the menu bar. I just don't understand why this daft thing was introduced in the first place.
There's no reason to remove the previous config flag. Please Re-enable the past behaviour with the next update, at least until you solve this non-solution that's causing so many complaints and come up with a better one.
After I posted a comment saying I'd like to be able to drag and drop my most-used apps to the toolbar, I discovered that you can hit the extension button, right-click on an app's button, and select "pin to toolbar." That works for me: my favorite apps are immediately available, and the rest are contained in the extensions puzzle-piece, reducing toolbar clutter significantly.