Probably missing steps doing small lines?

Just making some small rulers for the kids when i noticed some of the mm indicators were not the same length as the others. When checking out the engraving path it are (of course) the last groups of lines. As you can see in these images, from around 7.5cm on the ruler the last 5 mm of every cm seems to go up by a tiny bit. The last group on the 15cm is the worst. The bottom line actually never sees the issue, but is also engraved in a different order probably due the letters and optimization.

So i thought maybe if i play with the optimization parameters i can get rid of it, but first i tested what it does without any optimization. Then it first engraved all the CM lines, then the next round it does all the first mm lines, next round 3rd mm lines and so on. When it does this, after every horizontal line it seems the Y axis jumps 1 tick or mm. ( Image is 90 degrees turned, but its the most left line with all the mm indicators jumping. I stopped the job halfway through since it didnt got any better )

Now my guess is im missing some steps due too fast movement somewhere?
Which parameters should i look at and which should i lower to test first, im not too familiar with the parameters in the ruide yet.
I just have this machine (Omtech 70w blue gray 70x40cm) as upgrade from my Atomstack A5. I’ve alligned the mirrors already. Checked the belts after i noticed this issue, they don’t seem loose or anything.