ChangeNotifierProxyProvider updates

[thesame]

Hello community! This statement from the documentation regarding ChangeNotifierProxyProvider seems somewhat questionable to me:

DON'T create the ChangeNotifier inside update directly ... Instead reuse the previous instance

There are cases when updating an existing notifier with new data is simply meaningless. A good example is authentication. If the first ChangeNotifierProvider gives User? value, and then the dependent provider creates either AnonInfo or UserInfo ChangeNotifier's.
I assume it's safe to do it like update: (context, userProv, _) => user.value == null ? AnonInfo() : UserInfo() but it contradicts the documentation.

What is the right way to solve this?