Github app state - docs out of date?

Referring to the docs here we should be able to preserve state by passing a query param e.g. state=AB12t

However in practice when navigating to, for example, (random marketplace app)

state is present on the initial install screen, however it is dropped after selecting a repo. Becoming apps/kekschat/installations/new/permissions?target_id=42340374

Are the docs out of date or am I missing something here?