I've added your vote to the open feature request for an RSS feed image provider.
In the meantime, you can stop DisplayFusion from changing the wallpaper without affecting the other functions, but then you wouldn't be able to set different wallpapers per screen. To disable it you can just clear the images from each monitor, and then also disable the "Warn me if my wallpaper needs adjusting" option in the Wallpaper Settings.
Thanks!