Diana & Ahri W(spell) revealing their location in bushes

I have noticed this a few times. Diana and Ahri both have spells particles that orbit their character, and I've noticed that those particles aren't always hidden by the bushes in river (particularly the tiny bush in the middle of the river).

As a silver noob I like the idea of exploiting this to my advantage, and as a player I don't like knowing these kinds of bugs exist and can be taken advantage of.