Sudden hiccups when cutting

I think it’s time to ask for help.
I have a 50W CO2 (Chinese) laser cutter/engraver. It’s been few months now that when cutting SOMETIMES there are some “hiccups” on the step motors that cause straight or curved lines to shift (pictures bellow). What I don’t understand is that those backlashes are random because I’m cutting the same piece over and over.
I’m only cutting 1/4 birch plywood at 8-10mm/s at a power not greater than 20%, and a speed of 20mm/s at a power of 9-10% when engraving.
I already tried the following:
Adjust/loosen belts (all axis)
Clean tracks
Recalibration of mirrors
Reduce cutting speed
Reduce traveling
Different softwares: Lightburn and RDworks

Any suggestions?
Thanks in advance

Ruida RDC6442G-B(EC)

I’ve experienced similar issues when I send the file from my computer and hit start in Lightburn. If I send it and walk to the laser to hit start, it never has a problem. I read something that says the controllers have limited memory and the info doesn’t get to the controller in time.