The rotary drive belt is likely not tensioned properly. The squish at the beginning is where it changes direction, and the first few lines are just being scanned on top of each other as that slack is taken up. It’s really common.
The simplest thing to do is draw a short line under the bottom of your design (about a mm away) set to 0.1% power, and make that your first layer. The rotary will spin to that point, draw basically nothing, then retract the mm gap to where your design starts, taking up that belt slack in the process.
Of course, the correct thing to do is fix the mechanical issue, but if it’s a closed unit that might not be possible.