EXIF data is not taken into account in the slideshow in the background. See this foto here: https://www.mageialinux-online.org/forum/topic-24500-1+slide-show-kde.php#m235095
Can't reproduce in: Plasma: 5.11.5 Apps: 17.12.1 Frameworks: 5.42.0 Qt: 5.10.0 Kernel: 4.14.16-1-MANJARO