In brief
git verify-commit checks a commit signature using the supported mechanism and configuration. That is separate from the quality of the code it contains.
Useful to know
git verify-commit checks a commit signature using the supported mechanism and configuration. That is separate from the quality of the code it contains. [1]
Establish which key is expected and how it is linked to the author. A cryptographically valid signature from an unknown key does not automatically prove the intended identity. Signing and code review complement rather than replace one another.
Sources
For further detail and to check the information: