I think the issue here is, that you might expect a visual feedback in the window you have opened, in this case the preference window, and not on the main application window of Pamac. Especially it might be an issue on mobile, as then the windows are stacked on top of each other. So having the progress bar under the refresh mirrors button would make sense, as on mobile you won’t see the main window not at all.
And again: open issues, otherwise we won’t prioritize them. Most of our developers have no time to lurk into the forums!