The screen darkens when using the "Holy Light" spell (The Elder Scrolls 5: Skyrim)

when me or my companions cast a sacred light spell on enemies, the screen starts to darken. BUT! it darkens only when the spell hits the enemy, it darkens only, as it were, in the "world" all the panels that are, life, mana, power reserve, the compass is visible to the serhu, it is not affected. when the caste stops, everything becomes gradually normal, help pzhl to solve the problem.