all events get read

main.rs

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(
            Update,
            (
                produce,
                read_one.run_if(on_event::<MyEvent>()),
                read_two,
            )
                .chain(),
        )
        .add_event::<MyEvent>()
        .run();
}

#[derive(Event, Debug)]
struct MyEvent;

fn produce(mut writer: EventWriter<MyEvent>) {
    writer.send(MyEvent);
    info!("\n\n");
}

fn read_one(mut reader: EventReader<MyEvent>) {
    info!("read one");
    for e in reader.read() {
        info!("event 1");
    }
}

fn read_two(mut reader: EventReader<MyEvent>) {
    info!("read two");
    for event in reader.read() {
        info!("event 2");
    }
}