Agreed, having to manually close the intrusive download tray pop-up is very annoying and had I known it would be a "feature" of the new version of the browser I would have avoided updating for as long as possible.
At the very least add a settings toggle to turn off the auto open panel function. it's REALLY annoying and had I known it would be a thing I would have stuck with the previous version of Firefox for as long as possible.
