That looks like under-extrusion to me.
Here's the quick "tune your extruder" arc:
- E-steps. Mark your filament about 125mm from a known reference point, extrude 100mm, measure again. What percentage of 100 did you get to? Adjust your e-steps accordingly and try again. You should never have to mess with this number ever again unless you physically change parts in your extruder. More detailed guide
- Temperature. Print a temp tower. Choose the temp that looks the best and offers good layer adhesion. Your filament will extrude differently based on your extruder temp
- Flow rate / extrusion multiplier. This will require more typing from me, but there are a number of ways you can generate test prints for this, so check the linked guide. More detailed EM multiplier guide.
After you get #1, never touch it again unless you change things like your extruder gears. #2/#3 are a good idea whenever you start a new roll of filament, although I personally don't bother unless I'm trying a new material, brand, or color.