Do we use the docs of Android and iOS to integrate or use the FlutterFire docs even if it is using old versions?

[YazeedAlKhalaf]

Do we use the docs of Android and iOS to integrate or use the FlutterFire docs even if it is using old versions?

I mean, for instance, the FlutterFire docs instruct to add this dependency:
classpath 'com.google.gms:google-services:4.3.3'
but the firebase flow of adding Android app mentions this instead:
classpath 'com.google.gms:google-services:4.3.5'

And some other implementations are in Firebase for Android but not mentioned in the FlutterFire docs. So do I follow only FlutterFIre docs or get the latest versions and follow the Firebase Android docs? And any reason for using the old version?