On Firefox for Android, while scrolling certain websites such as Google and Wikipedia, the toolbar disappears normally while scrolling down, but periodically reappears without me changing anything. This is not an issue with the way I scroll, as this issue started several weeks ago. This is likely an issue with my phone's touchscreen, but it doesn't happen to this degree in other apps, and it doesn't happen at all in other browsers.

Is this a common issue with a solution? And if not, is there a way to permanently pin the toolbar to the top of the screen so it doesn't disappear after scrolling down?