When Haruna goes to fullscreen after opening a video, the first *fullscreen transition* effect is completely different than all the other ones. My suspicion is that the *fullscreen transition* effect only loads after the user makes the player go fullscreen, which doesn't leave enough time to load Haruna's own effect for it.
Created attachment 177188 [details] Notice the effect when going fullscreen for the first time.
Can't reproduce. Open another bug report if you can reproduce on openSUSE Tumbleweed.