Is that an application problem or other problem?
Devices have been tested before delivered from factory to customers.
If you want to do some analysis of the silicon, kindly contact your cypress distributor or cypress sales. They can help you further.
Perhaps your external circuit depends on the timing of the device being in
a certain range - and no faster - and the processes have gotten faster?
It could also be something completely unrelated to the Cypress part, such
as Purchasing substituting parts, board contamination, a problem in the
test circuit, inappropriate use, ...
Have you tried swapping in an old Cypress part on a new board, or a new
Cypress part on an old board?
The application is on using capacitive sensors with CSD module. External components and the PCB are always the same...
In the attached picture you can see the symbol of a square in the lower right and then a "C". In some chips of the same type I only see the square: what is the difference?