I think I found the issue.
The script isn't bugged per say, it's just defined to always override retroactively and matches all of the GitHub releases to Changelog.rst, so if we release a version manually, when this file is changed everything else will be changed also in GitHub releases.

This means that to release a new GitHub release, we need to just push a commit to this file.
That means, to get 5.3.0 message back we need to create a PR to Changelog.rst and it should be fixed automatically @auvipy

So I suggest closing the PR and leaving this script intact, it makes sense to me and it does work.

That being said, this PR is great for documentation of this issue for future cases ❤️

We can use the release notes generator manually when we're committing a new version in Changelog.rst and copy it, adding our personal note as well that will be kept as it's in the rst file

good idea