It isn't that frightening as everyone always comes up OK especially the superheroes and the akumatised victim.
Chloé (Queen Bee) may be rude to Marinette (Ladybug) throughout the whole series. It IS played for laughs though.
Lila is considered a complete liar, trying to manipulate Marinette's friends. Her actions are unpleasant and atrocious.
The appearance of the akuma villains and sentimonsters is not especially scary, as most of them have cartoonish designs such as a man made of bread or a witch crossed with a cyclist.
When someone is akumatized, one of Hawk Moth's butterflies called akumas infects an object causing darkness to surround their body, transforming them into an akuma villain with Hawk Moth saying he's giving them power to take revenge. This usually happens at least once per episode.
None for neurodivergent viewers.
None/Mild in a lot of episodes.