The point of this thread, I think, is that "should it be the push date or the commit date". You can work on a branch for two months and finally squash it
I would have to check, but if you squash it, you create a new commit => wouldn't that give a new date? (Don't know maybe it keeps one of the existing...)
It may be kept if you you just rebase (including maybe re-order). Also maybe if you just amend?
And for that reason "commit" date is sometimes meaningless. If you make a merge request, then we will likely rebase it right before we merge it (Gitlab IIRC even allows a policy that enforces that). => But then the commit dates of all the commits in that branch will be changed.
So if you authored that long before, then that is lost.
Push isn't possible. Well GitLab could add it on top of git, but within git itself it can not exist.
Well, you would need to store the dates outside the commit.... => because if it was part of the commit, then when you push, it would be added, and that changes the SHA of your commit. But if you have other git clone/servers to sync with such a change would cause trouble.
Also a commit can be pushed to different remotes, and then each remote has a different date for that (another reason it couldn't be part of the commit)
So push date (as interesting as it sounds) doesn't work well (again, gitlab could store it outside of the git data, but that is some work for a tiny effect)