When investigating JENKINS-57772 I have found that contrary to this comment the git plugin does not set the timestamp for annotated tags to the tag date.

Currently I can not find any references in the git-plugin source which instantiates this class with an annotated tag's timestamp, however I can find references where it does it with the underlying commit's date:

• https://github.com/jenkinsci/git-plugin/blob/5e7d735c4d24a6e54a7494381a0f6e80dd5f948c/src/main/java/jenkins/plugins/git/AbstractGitSCMSource.java#L765
• https://github.com/jenkinsci/git-plugin/blob/5e7d735c4d24a6e54a7494381a0f6e80dd5f948c/src/main/java/jenkins/plugins/git/AbstractGitSCMSource.java#L990

It seems like this behavior causes the problems outlined in the issue above. Reproduction steps also can be found in the said issue.