Arduino randomly process commands

Hi everyone , in first im sorry for my bad english , im french and i think my english is very bad :smiley: so that is my project :
-Raspberry Pi 4 running latest Raspbian desktop with blynk local server and blynk-ser(for arduino usb)
-iOS with blynk app as remote controller
-and L9110S motor driver to drive 12V relay
and my problem is that the arduino works only when he wants , i press rapidly for example button 1 , the relay turn on then off but at a moment (randomly) it stay stuck on or off and the RX led stay off but the TX turn on when he receive comands … so did you think its hardware or sftware problem ? ( don’t have serial to ttl for debug but im still waiting for this )
thanks you and sorry for bad english