Inconsistency in displaying the time zone using datetime.getDisplayValue()

I have an email script which results a date and time after at certain duration. i see inconsistency across the instances with the same code the timezone is being print on the DEV instance, if the script is triggered on TEST instance it does not show the time zone in the output.
What can be the probable cause of this inconsistency?


please suggest.

thanks

Akansh.