Take Mamiko Noto. She is the narrator for Hataraku Saibou (and a few other shows). On the website, she is only listed as the narrator for the anime she actually narrated. However, in the app, any anime on my list (or at least the anime that I've visited resulting in all the character/actor data being downloaded) that has a narrator lists her as the narrator for that show. This happens for any actor that has narrated an anime, not just Mamiko Noto of course.
As a side note, since the app only lists characters for an anime (you have to go to the character page to find the associated actor), it's basically impossible to find the actor who voiced the narrator in a given show. This is because once you go to the narrator page it (correctly) shows all actors who have voiced a narrator. On the AniList website, the actors (for the selected language) are shown right next to the characters, so it's possible to directly go to the actor page and avoid this issue.
Take Mamiko Noto. She is the narrator for Hataraku Saibou (and a few other shows). On the website, she is only listed as the narrator for the anime she actually narrated. However, in the app, any anime on my list (or at least the anime that I've visited resulting in all the character/actor data being downloaded) that has a narrator lists her as the narrator for that show. This happens for any actor that has narrated an anime, not just Mamiko Noto of course.
As a side note, since the app only lists characters for an anime (you have to go to the character page to find the associated actor), it's basically impossible to find the actor who voiced the narrator in a given show. This is because once you go to the narrator page it (correctly) shows all actors who have voiced a narrator. On the AniList website, the actors (for the selected language) are shown right next to the characters, so it's possible to directly go to the actor page and avoid this issue.