Where would that directory come from? What is it supposed to contain?

I'm so sorry, this /build directory is the output directory I specified, it shouldn't appear here, I will delete it.

Please remove that file. If present, this is expressly meant to be shared via git.

These files out/ CMakePresets.json CMakeUserPresets.json are automatically generated by opening the project in CMake mode in VS.
The out/ is the compilation output directory, I will change it to somewhere else. But CMakePresets.json bothers me, I can't delete it, and it seems to be automatically generated by the Qt plugin.

// CMakePresets.json
{
  "version": 3,
  "configurePresets": [
    {
      "hidden": true,
      "name": "Qt",
      "cacheVariables": {
        "CMAKE_PREFIX_PATH": "$env{QTDIR}"
      },
      "vendor": {
        "qt-project.org/Qt": {
          "checksum": "wVa86FgEkvdCTVp1/nxvrkaemJc="
        }
      }
    }
  ],
  "vendor": {
    "qt-project.org/Presets": {
      "checksum": "67SmY24ZeVbebyKD0fGfIzb/bGI="
    }
  }
}