How to solve this 3D printing issue : it graze the top of the last layer when it travels across the print and leaves a scratch

Check your print bed leveling: If your print bed is not leveled properly, it can cause the nozzle to be too close to the bed or too far away, which can result in the nozzle scratching the top of the print. Make sure your print bed is level and adjust it if necessary.

Adjust your print settings: You can try adjusting the speed and acceleration settings for your printer. Printing too fast or with too high acceleration can cause the nozzle to graze the top of the print. Slowing down the print speed or decreasing the acceleration may help.

Increase your layer height: Printing with a thicker layer height can help reduce the number of times the nozzle has to cross the top of the print, reducing the chances of scratching. However, this will also affect the overall print quality and accuracy.

Use a different print surface: Some print surfaces, such as BuildTak, can be more prone to scratching. You can try using a different print surface, such as a glass bed, to reduce the likelihood of scratching.

Consider using a different printing technique: If the above solutions do not work, you may want to consider using a different printing technique, such as using a raft or support structure, to reduce the chances of the nozzle touching the top of the print. However, this may add additional time and material to your print.