the itch.io app is directly linked to the website. sometimes there are errors sure, But i use it for pretty much every vn and game associated with Itch.io. When you publish an update to your game, it also sends the update to the app as well as the website
most vns dont experience this issue, But this specific one is common. it sometimes fixes itself by the next update, othertimes not so much.
you dont have to do this as most of your readers will just download from the website, but if you wanna expand your userbase, I recommend you at least look into the app. should save you a lot of time and effort as well.