Sorry for the long silence, I was away from home.
I found what the issue is: it’s one of the 2 kinds of LED that I purchased that creates it…
I have replaced them by the other model (LED strip), and voila…
I though it was not the hardware because:
- Some from the strip also had wrong colors. I suppose the signal was polluted though the individual LEDs?
- When I swapped the 2 first individual LEDs, the wrong colors remained the same, according to their position, not to the LEDs itself.
Thank you very much for your help Mike!