A bug in VSCode’s C/C++ extension might have destroyed your toolchain or Arduino packages. Please see PlatformIO is Broken for any esp32! - #17 by slopsjon to ensure that the extension’s version is from the stable channel.
Then, remove all folders inside C:\Users\Simon\.platformio\packages\, C:\Users\Simon\.platformio\platforms\ and C:\Users\Simon\.platformio\.cache and rebuild the project. PlatformIO will redownload its needed packages.