the issue come from the line : "#include <Arduino.h>"
I have possibly same issue here since a few days ago. Platform: Espressif 32 PIO Home 3.0.1, Core 4.1.0 Project can be empty one, just created from scratch.
The error is
#include errors detected. Please update your includePath. Squiggles are disabled for this translation unit. following by file path and name. More open files cause more errors of the same type to be displayed and counted.
On some files each include error is followed by something like:
cannot open source file "stdbool.h" (dependency of ...) C/C++  [1,1].
I tracked the problem to include path in
Adding three lines to win32 includePath (and saving the file) promptly eliminates the problem.
Now I don't claim they have to be exactly these lines, since I used trial and error method to tell intellisense how to find stdbool.h, but it somehow works.
The lines are:
"C:/Users/usernamedir/.platformio/packages/toolchain-xtensa32/xtensa-esp32-elf/include/c++/5.2.0/", "C:/Users/usernamedir/.platformio/packages/toolchain-xtensa32/xtensa-esp32-elf/include/c++/5.2.0/xtensa-esp32-elf/", "C:/Users/usernamedir/.platformio/packages/toolchain-xtensa32/lib/gcc/xtensa-esp32-elf/5.2.0/include/",
Sadly, this works only until VSCODE is restarted. Since it's all about an autogenerated file, I tried adding these settings to various config files (global, workspace, project), but with no success. I tried this on three computers with same results.