In event sourcing application state is derived from playing back a history of events in chronological order. This could be done in an aggregates or a projection.
So if you want to do event sourcing correctly, you need to make sure you can replicate your state by replaying your event in sequence.
Reference
Hoffman, Kevin. Real-World Event Sourcing: Distribute, Evolve, and Scale Your Elixir Applications. The Pragmatic Bookshelf, 2025. The Pragmatic Programmers.
Highlights or timestamps
The state of any given application is determined by a sequence of immutable events that occurred in the past.
— highlight from Highlights of Real-World Event Sourcing
The fundamental idea of Event Sourcing is that of ensuring every change to the state of an application is captured in an event object, and that these event objects are themselves stored in the sequence they were applied for the same lifetime as the application state itself.
— highlight from Highlights of Real-World Event Sourcing