Yarn is absolutely safer than npm in terms of determinism and lock file preciseness. I think it was actually one of the main goals of yarn v2 to be fully reprod

Yarn is absolutely safer than npm in terms of determinism and lock file preciseness. I think it was actually one of the main goals of yarn v2 to be fully reproductible and deterministic. After performance, the other main reason we moved from npm to yarn was exactly that it completely removed an entire class of bugs we had that were caused by incompatible packages versions installed in various places of the repo. In exchange of that, yarn will warn if it encounters packages that don’t declare their reps and peerDeps correctly. And there are loads of those. if you want to be safe and remove these warnings, you will have to either ask the package authors to declare their depa correctly, or fix them yourself manually in your yarn YML file.