Palpatine seemed to have died when Darth Vader chucked him into a pit on the second Death Star, but he had found a way to cheat death and hide for about thirty years. The First Order had made Star Destroyers that improved on the design flaws from the Imperial ones and were bigger. These were known as the Resurgent-class Star Destroyer. Despite this, Palpatine was planning to make ones that looked like Imperial-class Star Destroyers scaled up to about two and a half kilometers long that had axial superlasers that could destroy planets built into all of them. These were to be called Xyston-class Star Destroyers.
Besides keeping the construction a secret for decades and getting the resources for a thousand of them, miniaturizing the superlaser technology was difficult. But the First Order had found a "Shrink Ray Mark Six", which Kylo Ren took to Palpatine, who realized how useful it would be to his fleet of planet destroying Star Destroyers and used the Force to take it from Kylo.
Even with advancements in miniaturizing technology, the superlasers were still too big to fit on the bottom of the Xyston-class ships like Palpatine wanted, so through ordering minions due to being on life support and wanting to transfer himself into a better host body, they used the shrink ray and the axial superlasers could fit on. That said, a new design flaw was that destroying the lasers destroyed the whole ship. Why was this the case? Because the lasers were attached right to the reactors of the ship due to that being needed to have the power to destroy planets.
One of the first of these ships went out and destroyed the planet Kijimi, but while Palpatine awaited the news, he lost communication with them. The rest of the ships went out to intimidate the galaxy into obeying Palpatine, but one of the first to have the shrunken superlasers built into it seemed to self-destruct.
"What happened?! Unless someone built a design flaw into these, they shouldn't have a self destruct function!" Palpatine said.
The truth became apparent when the still intact axial superlaser started growing back to its original size before the shrink ray was used on it. To his horror, Palpatine discovered that the effects of the Shrink Ray Mark Six were temporary. Given that every single one of the Xyston-class ships used the shrink ray to get the superlasers to fit, every single one of them seemed to self-destruct. Palpatine, who the galaxy had already discovered was back when he announced it, wondered how much of a setback this was going to be.