Currently, Infuse displays the backdrops provided for each movie in the Up Next row at the top of the starting screen. While I do love my backdrops and curate them carefully, using the thumbnails provided in Jellyfin, or other video sources supporting thumbnail assets, would make much more intuitive sense. The current behavior should be adjusted, or at least be complemented with an option that lets you choose.
I’m well aware that some content sources like Plex don’t support any assets besides covers and backdrops. In this case, Infuse could still revert back to using backdrops when no thumbnail can be found just as it reverts back to using names instead of logos if they aren’t supported.