Welcome to the SeeMeCNC Community

I'm still calibrating my setup and it's getting better with every iteration.
I've got stringing down now but my first extruder had a non-centered drive gear. So i've build a new one. Direct drive spring loaded with mk7 drive gear like the upgraded makerbot one.
But now i het the result as can be seen in the attachments.
It's the famous treefrog @ 50% (2 cm diameter approx).

It starts of good. Strong adhesion to the build plate, good infill and no gaps between infill and loops. No skipping off the extruder. I let it run unattended. But halfway through it goes bad. It looks like starvation but how can that be almost at the end?

This could be a heat related issue, as your print gets near the top it is getting too hot due to the head remaining so close to the last position it was in rather than swinging away and letting a little cooling occur. Try running a cooling fan for the entire print except the first layer. I would also try printing 5-10c cooler and see if that helps. Your print looks too hot from the start to me, because of the lumpiness.

What temp and material are you using?

I'm using PLA @200 now but good point. I'll try running it at 5 degrees lower. And than repeat it until 180/185 or so.