My personal opinion is that only THE author must be the one allowed to change the licence of his own code, not another person.

Is that correct?

It is the **holder** of the rights. As non-native speaker I am not sure I am using the right term, so I will describe.

I am employee of Red Hat. When I write a code then I am the author. The authorship cannot be transfered. But at the same time I am owner of the rights and that can be transfered. In my case, in my employee contract is written that the rights for the work related to my employement goes to Red Hat and Red Hat is the holder of the rights. They can decide what to do: release it under any license, sell it, close it, ... and they re-license.

When you contribute to a project you may agree (not neccessery sign) Contributor Agreement (e.g., [1] in case of Fedora) which may give some rights to the project owner.

Sometime the change of license can be easy and project owner can do it. But sometimes it can be tricky as in case of OSM re-license [2] where every single contributor had to agree with license change.

[1] https://fedoraproject.org/wiki/Legal:Fedora_Project_Contributor_Agreement

[2] https://blog.openstreetmap.org/tag/license-change/

Miroslav