To get all Ajan Kloss Space Kyber Bricks and characters in Lego Star Wars: The Skywalker Saga, you need to complete two side missions: Hoth and Bothered and Jedi Text Message, and destroy one Kyber Brick Comet. The tricky part is that one of those side missions, Jedi Text Message, actually starts at the Resistance Camp on Ajan Kloss.
How to complete side mission: Hoth and Bothered
Switch to a Protocol Droid and talk to the NPC ship (marked as a “character” on the map), flying around Ajan Kloss Space. It turns out to be a Cowardly Courier. Accept the courier’s Hoth and Bothered side mission, then travel to Hoth Space. On the way, you’ll be attacked by three squadrons of TIE Fighters, so fight them off, then report to the Rebel Ship when you arrive.
Target: Kyber Brick Comet
Reward: 5 Kyber Bricks
The Kyber Brick Comet is marked on the Ajan Kloss Space map. Find and destroy it to get five Kyber Bricks and some studs too.
How to complete side mission: Jedi Text Message
Reward: 1 Kyber Brick
This mission is probably the one you’re stuck on because the Jedi Text Message side mission doesn’t start in Ajan Kloss Space. Instead, it begins on the surface of Ajan Kloss itself, at the Resistance Camp. You have to complete the Second Breakfast puzzle to unlock the Jedi Text Message side mission, so that Beaumont Kin will be available to give you the mission. After completing Second Breakfast, find Beaumont on the ground next to the Tantive IV, talk to him, and accept the Jedi Text Message side mission. Read the Datalog next to him, and you’ll see the following clue:
“Through shapes in space, in order you fly, counting the sides, from lowest to high.”
The first clue in this riddle is “in space,” so travel to Ajan Kloss Space. Find the cluster of four strange-shaped asteroids away from the main asteroid field (they’ll be marked as a Kyber Brock on your map). Fly through the asteroids starting with the one with the lowest number of sides, and finishing with the one with the highest number of sides. So, in this order: circle, triangle, square, star. Get the order right, and the Kyber Brick will appear in the middle of the four shapes.