Issue Summary

When the Default time zone is set to any of the below time zone in user profile, any update by the user on the issue modifies the time configured in the Date time picker field by +1/-1 hour. and 3 hours behind in case of Antarctica/Casey.

Africa/Cairo: true: 1h behind
Africa/Juba: true: 1h ahead
America/Mazatlan: true: 1h ahead
America/Bahia_Banderas: true: 1h ahead
America/Merida: true: 1h ahead
America/Mexico_City: true: 1h ahead
America/Monterrey: true: 1h ahead
America/Ojinaga: true: 1h behind
America/Godthab: true: 1h behind
Antarctica/Macquarie: true: 1h ahead
Antarctica/Casey: true: 3h behind
Asia/Tehran: true: 1h ahead
Europe/Volgograd: true: 1h ahead

The issue is reproducible in Jira version 9.12.5, 9.4.23 and multiple other versions with both Java 11 and Java 17.

Steps to Reproduce

1. Set correct timezone that has no issues -Ex: Europe - Warsaw, Asia - Kolkata.
2. Update the ticket with no changes - all works fine, date time field "Planned Start" is not updated.
3. Change timezone in the users preferences to Africa - Cairo.
4. Update the ticket with no changes.
5. Custom field of type Date time picker is changed by 1 hour.

Expected Results

The Date time picker field value should not be changes unless explicitly changed by user

Actual Results

The Date time picker field value is updated by +1/-1 hours based on the timezone selected in the user profile.

Workaround

• Set the timezone in user profile outside of the timezone mentioned in the list above.