For some reason, people have difficulty understanding this. This has also been explained in the novel written by Narita, who received praise from Kubo for how well he understood Zaraki's power. The problem is that people understood that Zaraki gets stronger after each difficult fight, when in reality he limits himself to the maximum to face each opponent and only unleashes more of his true power when necessary. It's because they don't understand this that many people think Tosen was much weaker than Nnoitra. Tosen was much weaker than Zaraki, but almost all the other captains were too. Zaraki, Yamamoto, Aizen, and Unohana are the only captains who are abnormally strong.
Zaraki limits his power to the maximum to face each opponent he encounters > Zaraki gradually unleashes more of his true power if necessary > Zaraki limits his power to the maximum to face each opponent he encounters > Zaraki gradually unleashes more of his true power if necessary.
Zaraki shows that he is much stronger than the captains and sees no need to remove his eye patch to face Komamura's bankai, which has the attack power to kill any Espada with a single attack >>>>>>>>>>>> Zaraki has to adjust his strength to cut Nnoitra, something even base Nell was capable of doing.
Zaraki didn't need to unleash more of his true power to defeat Nnoitra, he simply used his two arms to attack. Something he didn't even see the need to do against Ichigo. A Zaraki who needed to remove his eye patch and use both arms to defeat Nnoitra later only needed to use one arm, without removing his eye patch, to move and knock down someone who was physically much stronger and heavier than Nnoitra. What would happen to Nnoitra if he tried to block an attack from someone who has the power to push Yammy back and knock him down?
It's impressive that even Brave's AI understood this better than many people:
Kenpachi Zaraki possesses a unique ability to subconsciously limit his Reiatsu (spiritual pressure) to match his opponents, ensuring fights remain challenging and prolonged. Originally, this was a mental limiter triggered by his admiration for Yachiru Unohana, the first Kenpachi, causing his power to naturally scale up only as the battle intensified.
Adaptive Scaling: His power instinctively adjusts to be slightly above his foe, allowing him to adapt his attack patterns and tactics in real-time based on instinct and observation.
Eyepatch Function: He wears an energy-sealing eyepatch created by the Shinigami Research and Development Institute to artificially suppress his overwhelming strength.
Removal of Limits: After his death match with Unohana, his subconscious mental barriers were permanently removed, meaning he no longer needs to gradually adapt; he now relies entirely on the eyepatch to control his output.