Unwanted laser firings (stripes) (overscan)

When i engrave a structure, sometimes unwanted stripes appear outside of the structure, like a overscan with active laser…
Extended K40
MKS sbase, smoothieware with clustering (c3d)
Pwm frequency 5kHz (200microseconds)
Connected to L
Max current limited by poti on IN
PC connected by boosted USB2.0 cable 4m long.

Please share more. What are you using to drive this K40?

Machine info… done

It looks more like an error in the file than overscan. Do you have this problem all the time and only in the Y or also in the X direction?

it happens only sometimes, not securely reproducible.
may be the USB connection is the reason

… it also looks most like “noise”