I agree with RyanCarlyle on this:
Your print isn't cooling fast enough.
Please regard this answer of mine that covers a few options to help with the issue you're encountering. Pay particular attention to the layer times, and active cooling.
The essential take-away from my answer (linked above) is this:
- Increase Layer Times. Increasing Minimum Layer Duration (Device Settings -> Minimum Layer Duration) will provide the material with more time to naturally cool down closer to its environment's temperature. What this does is ensure that the latest layer is mostly solid before the machine begins printing the next molten layer. If you don't let the previous layer of plastic solidify enough, then plastic gets pushed/pulled around when the machine moves, adding more plastic; thus resulting in the issue you see in your images. The caveat with this approach is the obvious impact on the overall runtime of your print and should ideally be done more or less as a last resort.
- Active Cooling. Active cooling is typically done using an additional fan, often times mounted directly in front of the extruder. The act of active cooling provides a quicker and more direct means of cooling the printed plastic. However, depending on machine design, you may see more variability on other places such as dependability in extrusion temperatures. This can be more detrimental with cheaper spools of PLA and especially poorly designed machines that can't properly maintain extruder temperatures. Active cooling is, however, very common and seems to work for the majority of 3D printer enthusiasts and doesn't impede on runtime.