When selecting a Release date, we only have the option to select the date and the time is automatically set to midnight (0:00).

However, the release date changes depending on the User Timezone.
For instance, a release date set as April, 16th 0:00 on Jira timezone GMT-5 will be April, 15th at 11 pm for a user with the user timezone GMT-6.

Steps to reproduce using a scriptrunner function:

note: Script Runner does consider Monday as the start of the week

1. Using a user located at the same timezone as Jira Server, for instance, using New York Location, define a version "A" with a release date set to the end of the week (2021-04-18) and another version "B" with a release date set to the start of the week (2021-04-19);

2. Create one issue "test-1" and assign fixversion "A" and a second issue "test-2" assigned to fixversion "B";

3. Create a JQL to find the issues using Script Runner functions:

 fixversion in releaseDate("on endOfWeek()")

4. Run the JQL: It should return the issue "test-1" assigned to the fixversion "A";

5. Edit User Profile and change the timezone to Chicago;

6. Run the JQL

Expected Results

Return the same issue

What is returned

It does return the issue "test-2" assigned to the fixversion "B"

Cause

For the user in Chicago, the release dates will be 2021-04-17 11pm (version "A") and 2021-04-18 11pm (version "B")