Ok…
That’s a follow up message on this topic.
One of the differences in Compilation/Upload between the Arduino and PlatformIO IDE is this line (in verbose mode !) :
Setting bit clk period : 5.0
This seems to be atuomagically added in Arduino IDE…
When you set upload_flags to “-Pusb -B5” in platformIO: it solves the problem as well (no need to modify the avrdude.conf file)
I’ll update the issue as well.