Stand-alone merge requests that are labelled, or parent issues, should be moved to the release project when closed. This is because I found it easier to update the CHANGELOG.md after all merges for a given release are completed rather than in each feature/bug fix branch. Otherwise, every feature/bugfix branch will have a merge conflict in CHANGELOG.md, making parallel work much harder to do.
This means when making a new tag, the release project has to be reviewed, and a pr for changelog changes has to be added based on "in progress" items. After a release tag is made all issues and merges in "in progress" should be moved to competed and a new prep merge should be made for the next release, setting the project version to the next expected release, and a header in changelog added for it so we know we are on an 'in-progress' release.