The blue dot functionality in the desktop app is extremely confusing currently. Apparently a solid blue dot represents both a podcast you have listened to completely as well as something you haven't started at all. Then the partial blue dot shows that you started it but didn't listen to the very last moments of the podcast - which you can see how much is still left on your progress bar. (Discussion around this topic and explanation here: https://community.spotify.com/spotify/board/message?board.id=desktop_windows&message.id=96074#M96074
I would like to suggest that the blue dot not exist at all. The progress bar should be blank if you haven't listened to it and the blue as much as you have listened to it. Why does it go back to grey after you have listened to it fully??? It should stay solid blue representing how much you have listened forever.
If you used the progress bar to show progress and never return back to grey, there is no need for the blue dot - which honestly is not intuitive of what it does anyway. You don't need to have multiple icons communicating the same info. The bright blue bar communicates perfectly if I've listened to it and how much I have remaining. Returning the progress bar to grey if you have fully finished the episode is the misleading part and should not happen. If I have finished it, it should show solid blue because I have listened to it.
I hope this happens and both the lack of blue dot confusion and clear use of progress bar is both intuitive and enjoyed by many.