⚪︎Discontent within the Empire
ISB inspector Dedra Milo had identified the threat of the rebels at an early stage and warned them about the Axis. The sporadic rebellion was actually systematically controlled.
The Empire, which thinks slowly in a centralized manner and takes bold action only after the threat is actually visible, did not realize this from an early stage. This is the downside of centralization.
Even within the ISB, there were many people who were self-protecting due to their desire for promotion. They did not think and act purely for the Empire. Contributing to the maintenance of the system was considered a great thing, and they were exhausted by fierce factional and power struggles.
⚪︎Yularen does not understand
Despite the strong warnings of the threat of the rebels, they did not reach the upper echelons. Since it was not an actual visible threat, it was ignored. If the rebels had been defeated at an early stage, the Empire would have been safe, but they were not able to deal with it appropriately. This was the Empire at that time.
⚪︎Thrawn is an understanding person
The Empire would later prove that Dedramilo was right, but the Empire's system, which was built during wartime, was not possible. The Emperor would later regret it.
Thrawn was probably the one who knew best. As an admiral, he wanted to point out the Empire's flaws, but he could not voice opinions that went against the maintenance of the system. Like Dedramilo, he was dissatisfied with the Empire. Dedramilo must have sympathized with many things about the advanced Empire that Thrawn was coming up with. Thrawn should read Dedramilo's reports.
⚪︎Not a yes man
Dedramilo secretly despised the Moffs who surrounded the Emperor. Tarkin is a prime example. The Stardust Project gradually came to the surface, but the scope should not be on large planets, but on rebel operatives Cassian Andor and Axis.
It would have been more beneficial to eliminate them quickly and at a low cost with pinpoint fire, rather than destroying the entire planet with an overly large cannon. If they had been able to get rid of Cassian Andor, the Empire would not have had to deal with rebellions later. What a waste.
In the end, Thrawn only started planning the First Order after the Emperor's death. It was too late. It had been a long time since Dedramilo's warning.
Even after losing the Emperor, Lord Vader, two Death Stars, and Tarkin, the Empire was unable to stop the rebellion.
The New Republic will judge the defeated Empire, but they are surprised that Dedramilo warned them from within the Empire at such an early stage. It perfectly showed the Empire's flaws. Despite this, they mocked Yularen, who was underestimating him at the time.
But they never imagined that the First Order's plan was progressing behind the scenes.
The report left by Dedramilo will be useful for the First Order plan.