Why do so many people confuse Google's Firebase (cloud API) with Google Services Google Firebase App Indexing (search results)?

Why do so many people (including myself, at first) confuse Google's
Firebase (cloud API) with Google Services Google Firebase App Indexing
(search results)?

Firebase (cloud related):
 <https://firebase.google.com/firebase-and-gcp>
 "Firebase and Google Cloud share three products: Cloud Firestore,
  Cloud Functions, and Cloud Storage. These are the same products
  that exist in Google Cloud, simply exposed for client-side
  developers via Firebase. You can access the same data from the
  server SDKs (Google Cloud) and the client SDKs (Firebase),
  so your frontend and backend teams can work in concert."

Google Services Firebase App Indexing (search related):
 <https://medium.com/android-news/firebase-app-indexing-for-personal-content-getting-personal-content-into-search-c52bfe45b3ac>
   "A note about privacy: The personal content index only exists
    on the user's device. None of the user's personal content is
    uploaded to Google servers and it only remains on the device
    while the app is installed. However, aggregated statistics
    about apps' usage of App Indexing and other system health
    information may be uploaded to Google servers."

Notice that the words "ON THE DEVICE" is supposed to make you feel
safer; however the caveat is that Google samples statistics frequently
(about once or twice a month in my experience) of this extremely detailed
private data (e.g., every map location you ever searched for and every
contact you've ever contacted and every app you've ever opened up, etc.)
means, as far as I can tell, it doesn't matter one bit if an application
has no Internet access... because Google does.

The main unanswered question is how to tell if any given app has
Google Services Firebase App Indexing incorporated into it, so that we know
to delete those apps, unless they're essential apps.

An example is I deleted Windy because it used Firebase App Indexing:
 <https://i.postimg.cc/qR8zr72r/appindex01.jpg>

And I deleted googlequicksearch, Google TV, T-Mobile and YouTube because
they used Google Services Firebase App Indexing (replacing them with apps
that did not use Google Services Firebase App Indexing such as NewPipe).
 <https://i.postimg.cc/Fs8GDLfX/firebase01.jpg>

The problem with Google Services Firebase App Indexing databases (which you
can only see if you enable Developer options) is they contain extremely
personal information about your activities, such as what you use GasBuddy
for (which is why I deleted Gas Buddy even as it's a useful app otherwise).
 <https://i.postimg.cc/nhCCVxmB/mapsloctrack03.jpg>

In summary, almost nobody (least of all me) knows how to describe the
difference between Firebase (the cloud Firebase) and Firebase App Indexing
(the search Firebase) so this thread is asking for a better description.

In addition, while the extremely private information stored on your device
for Firebase App Indexing isn't directly uploaded to the Internet, Google
clearly says they will (and do) upload statistics which we have no idea
what they are (nor how frequently they're uploaded, nor to whom) - so
another question is what happens to that extremely private data that is
stored in the Firebase App Index on the cellphone (other than it's included
in search results, presumably those run on the phone's data itself).

I barely know what Firebase (cloud) and Firebase App Indexing (search) do;
but it's really sad if I know it better than anyone else - hence - I'm
asking everyone else to pitch in so that we can tell, at a glance, which
apps use Firebase App Indexing so that we can avoid them, on sight.