2. filaments are damp.
3. Retraction is not set during slicing.
Solution
1. Set the correct printing temperature according to the information provided by
the filament manufacturer.
2.
Check if the filament has become damp (see How to identify a damp filament).
3.
When slicing in the Snapmaker software, the Retraction is set, and the
filament will be actively retracted for a certain distance when the extruder
is empty, so as to improve the flash or wiredrawing. The same effect can be
achieved by using the mixed color mode (support, two-color) and checking the
enable of the loading tower.