Between two releases there is a period where the code is changing and something is being tested. Naming that period is what makes it visible, because an unnamed one is a version that exists in the world and appears in no history.
About 1 min of reading
Name the candidate.
The tag
Before you run it, say out loud what it will print. Then open the answer.
Once a candidate is built, changes go to the next candidate, not into it. Editing a shipped candidate is what makes a version number mean two different things.
A candidate lists what it does not have compared to the planned release. That list is what a tester uses to know their results are about the release, not the candidate.
2.5.0-rc1 is a build that may still change. Anyone running it knows they are not on the release, and that knowledge is what prevents a bug report against a version that will not exist.
Users on 2.3 while the team builds 2.5. That gap is where the complaints come from, and a changelog that lists only 2.5 does not help them.
A release that fixes something a pre-release shipped needs a line saying so. Otherwise a person who hit it in the candidate searches a changelog and finds nothing.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.