When I post this question there is no 2C54 firmware yet. I did not see any option to edit the question.
My replacement AirPods Pro is running on 2B588, and I compared it with the old one (running on 2C54), the noise canceling ability has no difference.
The old one has bug that when I put one side of the AirPod, it is in noise canceling mode already (it is supposed to be on transparent mode and only switch to noise canceling mode after I put on the other side of AirPod). The replacement new one does not have this bug.
According to the testing of 2C54 from rtings, it is possible that NC was affected by the EQ adjustment on bass (for improve sound quality). Since Apple already stopped distributing 2C54, I guess Apple engineers already know the issue and working on fixing it.
BTW I think Apple should make a big change on their management of development. These years there are many problems happened that should be prevented before releasing : buggy iOS/macOS, bad keyboard design, false promise of AirPower (I guess there is some mid-level management person promise this to top-level guys and cannot full fill his/her promise.), iPhone signal problem, MacBook Pro 16-inch performance problem, iPhone X overheat problem, etc. And yeah, AirPods Pro firmware issue.
Seems Apple tried to improve the development performance by shortening deployment cycle, and hiring non-professional people as developer. But it turns out these fresh new developers created a lot of stupid bugs (macOS empty root user password issue, iOS hard-code out-dated time issue, etc. Even a fresh graduated student should not make this kind of naive mistakes. ). And many of them are just delivered to customer without any checking. Then developers were rushing to fix the bugs. Seems like they works a lot, but actually waste most of their time on fixing bugs, and ruins the user experience.
From the aspect of customer, Apple is no longer innovative (since their manpower is wasted on creating bugs and fixing bugs, nothing left for doing some creative work), Apple product quality is no longer solid (since it has a lot of bugs when delivered to user’s hand), and Apple products are more and more expensive.