Why backlight makes video transparent?

[nanikit]

Reproducible steps

log paste

1. Download this beatmap.
2. In cinema configuration download p.h. / Nekomata Okayu【Hololive】Romaji/English Lyrics
3. Play E+ difficulty.

Expected behavior

Show the following without transparency.

Actual behavior

[Kevga]

This is not related to transparency, those spikes are in front of the screen. The screen is being partially covered. The real issue seems to be that the screen is positioned too far up, it should be more centered by default on that environment.