Media picker help you to browse media (photos & video) inside without getting into the Gallary app to share them instantly
Try to get into Settings - apps - tab three lines in the right tab show system apps - look for media picker - battery - change to restricted
Some users faced battery drain issues with media pickers after downloading some specific games. If the issue exists after downloading games, try to uninstall it
I tried changing it to restricted, nothing happened. I'll try the games thing. I'd like to mention that the gallery app has been extremely laggy too, I don't know if it's got something to do with the media picker but it's really bad.
