I know this from N26 (not exact the same), i wished bunq had this too. If i scroll trought the Timeline. The App should also scroll down at the same time, if i scroll to past transactions.
There also should be highlighting the Transaction, wich is used for the actual saldo, wich the Timeline shows at this time.
On the other side, if you scroll down, the App Highlights the Transaction wich be used for the actual Saldo in the Timeline and the Timeline is moving too
See Sample: