Yes, you are right. It’s live quantization of the first note of the arpeggiator. If I start an arpeggiated sequence by pressing the keys a 1/10 of a second too late, it sounds awful. This is why many synths have a “midi clock” sync option, so that I can just press the keys whenever and it will snap the arp to the next midi clock time division, and sound perfect everytime. When you have four arpeggiators going on at the same time, it’s almost impossible to time them accurately without some help