Okay, until the bug is fixed, I've found a solution.
As I wrote before it's about downgrading the platformio version
but in my previous tests you didn't have use the flag -- force reinstall.
To get platformio back ok, do this:
Open Visual Studio Code
Wait for platformio to be loaded
click on the platformio icon on the left
from the choices that open up choose
Miscellanous -> new terminal
in the terminal window that opens type
pip install "platformio==4.0.3" --force-reinstall
press enter
Wait for the command to end.
then check the version change with
platformer --version
press enter
must show
PlatformIO, version 4.0.3
I didn't need to restart, but do it for safety.
Now build as usual and you'll see that the project.bin will load
perfectly on the printer