Under Extrusion
Try a Extrusion Testing
Check your Nozzle Temperature and your Print Time.
If your Material suffered from Moisture Exposure it might begin to Under Extrude due to a change in the Materials melt temperature.
Check the Filament Path for Snagging, look for:
Knots in the Filament
Damage to Filament Guides
Damage to the Extruder Housing
Check your Slicer Settings.
Check for a Clogged Nozzle, this might be more common after printing with your Bed Leveling set too low.
Check the Filament Feed Gear.
Check the Extrusion Spring. Do a Extrusion Testing while applying pressure on the Extruder Idler Tension Lever.
Check the E-Step Adjustment.
Check for Extruder Grinding.
Check if your Filament Diameter is consistent.
Also see:
Over Extrusion
Extruder