This is a known issue #4976 with Microsoft C/C++ extension and you can ignore it. It does not affect compilation or flashing processes.
A few workarounds:
- Please use the latest VSCode and PlatformIO Core (VSCode > Left Sidebar > PlatformIO > Quick Access > Upgrade PlatformIO Core).
- Remove
.vscode
folder from a project and restart VSCode. - Build project and restart VSCode again.
- Try to use 1 project per 1 workspace. This is a bug of C/C++ extension #4976. You can skip this workaround when this issue will be fixed.
Sorry for these issues. We work with Microsoft Team on improving C/C++ extension.