Do you get the same warnings on any of the tests or example projects in GLFW, or in this starter project: GitHub - juliettef/GLFW-CMake-starter: Use CMake to create a project with GLFW - Multi-platform Windows, Linux and MacOS. ?
I heard someone had a similar issue which I was unable to replicate:
If you can replicate the issue with any of the tests/examples etc. then it might be an issue with GLFW on your particular configuration, so knowing the exact OS details would be useful (Windows version).