It is confirmed that it does not come from the lamp. Because when I discossed the lamp of the app it was refitting. I did a complete reinstallation. I took the opportunity to change server. I chose the Singapore server and for now everything works. By cons, I noticed that when I turn on the lamp, it turns on for 0.5 seconds in blue and then regains its color memorized!
I'll keep you posted on what's next!