Looks like pretty classic underextrusion. Have you measured the filament diameter to see if it’s exactly 1.75mm? Even 0.1mm is enough to start causing problems. It’s prusament so should be good but worth looking! I can see underextrusion problems in more than just the problematic pillar, so worth playing with retraction and perhaps increasing temperature.
Looks like pretty classic underextrusion. Have you measured the filament diameter to see if it’s exactly 1.75mm? Even 0.1mm is enough to start causing problems. It’s prusament so should be good but worth looking! I can see underextrusion problems in more than just the problematic pillar, so worth playing with retraction and perhaps increasing temperature.
This happens from time to time regardless of filament, so I guess it might be the retraction settings, I’ll try adjusting them.