Some time in 2017, the Chrome team announced changes to the PWA installation experience called the improved add to homescreen experience. At the time, it was not as much about the automatic prompt, but that has been part of the change. It has more to do with how PWAs behave on Android and that it is more like a native application.
These changes were multifaceted and start with the web manifest scope property. This property is relatively new but allows the browser to know how to limit PWA functionality on an origin (domain name).
When you set the scope value to /, you are telling the platform that the progressive web application's capabilities apply to all paths within the origin. This may not always be the case, especially on larger sites and enterprise applications. Often, these sites are segmented into different applications...