Youtube video from Paramount Plus, it's the opening two scenes from the episode.
The Intended Goal
The first scene does the old standby of jumping us right into the middle of the story with a cool action sequence. We can see the new Spartans in action, and it's established that the mission is very desperate and straight forward: get on the ship, fight to some important location, use the device at all cost. We also learn that Perez and her commanding officer are not getting along, and that Perez is a bit bullheaded. All good things. Nothing groundbreaking, but not everything should be. Meat and potatoes make a satisfying meal.
The second scene reveals the twist, it's a simulation and everyone is safe. Which narratively is positive and negative. Positive, because one of our main characters didn't suddenly bite it in a cold open. It is negative because it just reversed all the drama that just unfolded and certain characters sacrifices' no longer matter; therefore you have to make it all matter again later - either as character development or subvert expectations that where just laid down. The scene goes on to do some explaining: Covenant ships are better but have weakness and here they are listed out. It ends with Kai passing on some wisdom to Perez.
The Immaturity
Taken in isolation, both of the scenes are fine. However, it is when you structure them like we see in the clip that issues arise. The most overt being, why in the world is a Special Operations team being told key pieces of their mission
after their mission? Perez clearly knew how to use the Spike, so why is Kai just now explaining the Spike and the shields? The framing doesn't suggest that this debriefing is a refresher on the mission but a full explanation as to why the team just did what they did. On a meta level, it makes the previous action scene, which made narrative sense - save the day, spike the machine at all cost - now feel unconfident in what it
showed us and that we clearly didn't understand. Now the narrative is taking precious moments to explain itself instead of doing more interesting things.
A Solution
This very easily could have been a micro heist sequence. It had the building blocks - here is the objective, here are the obstacles, here is how we get around them, and sudden twist. But the order is backwards. Instead, (and I'm not doing anything crazy, but meat and potatoes are filling) switch back and forth between the scenes. Start mid action then cut back to the briefing once the plasma starts flying, explaining why small and agile is better... at increasing survivability. Keep doing this until the end of the action sequence. Once, Perez wakes up back in the briefing room Kia reveals that the team has failed its Final Test and will suffer the consequences - idk, maybe tooth brushing toilets. Perez is ticked because there hasn't been an additional Elite in the bridge during any other simulation run. Kai passes her wisdom: War is random and unfair, be prepared.
In this structure, we remove any immersion breaking clunkiness and maintain all the positives of the original: a daring mission plus worlding building, setting the expectation - and therefore opening up how it will be subverted - for how the real mission is going to go, the relationship/attitude of Perez, and the UNSC attitude toward the value of the Spartan IIIs. Also, it keeps energy up for a longer period, stretching out the action over the top of the world building, which makes the info of the world building impactful at that very moment.
