1 Important Star Wars Detail Hints At Another Hidden Death Star Weakness

The Death Star's most famous weakness was its thermal exhaust port  but Star Wars has hinted the battle station had another critical weakness that would have become clear over years. Emperor Palpatine intended the Death Star to be almost invincible but he had not factored in Galen Erso's sabotage. Erso deliberately introduced an instability in the Death Star's reactor core and tricked the Empire into building thermal exhaust ports that would become tempting targets for the Rebel Alliance. As seen in the first Star Wars film later retitled A New Hope  the Death Star's thermal exhaust port led straight to its unstable reactor. Luke Skywalker was able to fire two Forceguided torpedoes down the exhaust port detonating the reactor.

The Empire's Second Death Star didn't have thermal exhaust ports meaning it would have lacked that weakness. Fortunately the battle-station was only partially completed allowing the rebel ships to fly directly through the structure and destroy the reactor. However wider Star Wars canon has suggested the super laser would have become flawed after prolonged use.

Kyber Energy Weapons Seem To Burn Out Their Crystals

During the very first days of the Empire following Star Wars Episode III - Revenge of the Sith, Darth Vader encountered Jedi Temple archivist Jocasta Nu who had survived the initial Jedi Purge with Palpatine's Order 66. This encounter is described in Charles Soule and Giuseppe Camuncoli's Darth Vader #10 in which Jocasta Nu placed her lightsaber into an ancient rifle. This used the kyber crystal as ammunition, effectively giving Jocasta a miniaturized Death Star at her disposal. After all the Death Star's superlaser works via the same principle with large quantities of kyber having been harvested by the Empire.

However Jocasta Nu only got off a handful of shots before the kyber crystal was spent along with her saber. This strongly implies using a kyber crystal in such as manner eventually burns out and destroys it. Applying this same concept to the Death Star it's possible the battle station would have only been able to destroy a handful of planets before the kyber would have been burned out. This would have meant the Empire needed to collect more and more kyber across the galaxy otherwise the Death Star's primary weapon would have become useless.

The Death Star Would Have Required Even MORE Kyber To Continue Operating

A constant need for more kyber could certainly be seen as a secondary weakness for the Death Star beyond the exhaust ports. The living crystals are rare and the Empire scoured the galaxy looking for kyber for the Death Star. The Emperor did eventually discover vast kyber deposits on the Sith planet of Exegol and the Empire also mined other worlds rich in kyber such as Ilum and Jedha, so Palpatine could have probably had quite a few worlds destroyed. However            it's likely the Star Wars galaxy would have eventually run out over time.