For example, this very site, when I click on a notification, it opens the page in the Android Instant App.
I normally browse Stack Exchange sites on mobile web (mobile web version is great!).
Ever since it prompted me to try the instant app, I haven't been able to make it stop using the instant app.
The only workaround is to long-press a link then open in new tab. Then I can navigate to the new tab to see the web version.