I’m more concerned about changing the license of contributions during merge to master or a release. That something goes wrong there and the whole code base ends

I’m more concerned about changing the license of contributions during merge to master or a release. That something goes wrong there and the whole code base ends up „poisoned“ with non free code. Software licenses need to work in a lot of different legislations, and it’s really hard to make a license that means the same thing in all countries.