So I come with a new problem.
Here is the image:
You can notice how the infill is getting thinner as it goes. The perimeters turn out quite well though…
The thing is, I keep the speed pretty low (30-50mm/s),
and the temperature is 230C (abs). So I am thinking, could this be a extrusion width problem or something more sinister, like nozzle clogging etc.?