I think Vicious is right on about the accel settings. The lines on the border of the image aren’t straight. You can see that the machine is resonating. I have this issue with vector engravings but never with the smooth sweeping motion in raster engravings. What software are you using and what is your feedrate?
Also, if you’re using Marlin then you are controlling the driver with 8 bit pwm(0-255) already.