This was only because I was power cycling the matrix to try out a new program and I am not going to run it without an external PSU.
Just to verify, when everything is on and running (PSU, Matrix, ESP32, etc..) then this isnt a problem, right? Only when the external PSU turns off for whatever reason its bad?
Or does this “Phantom powering” also happen with the external PSU and I just dont see it?