You should turn off ‘Flood Fill’ unless your designs are very simple - you need a really well tuned machine to be able to use that for complex paths, because it bounces all over the place. It looks like you just didn’t let the job finish, and that it skipped steps at some point, which explains the shifting on the C.
I did stop the project short as I figured it’s ruined now so didn’t more time.
I’m suspecting it was caused by a loose connection on the cable from Grbl board to the laser chip itself. It’s a crappy little connector that struggles to seat in properly on the laser board itself. I’ll need a more permanent connection I think
Tried another attempt at the same project and again another clear missed step issue. Connections look fine, workplace was secured well. No abrupt movements from the laser.
Double check pinions / pulleys, set screws that hold them in, and make sure couplers are all secure. Also check to make sure you don’t have any dirt or debris on the rails, or sticky spots.