Heater heating cycles of the heater causing the resin the shrink and expand during the print, making uneven surfaces.
The orientation of the print combined with not enough supports is not Ideal.
test run with turning off the heater will confirm the cause, the problem happens usually with users live in cold-weather regions, better heat-loss protection for the Moai will most likely fix the problem (this is based on user’s result).
Make sure the densest part of the model is on the build plate facing towards the red, put model at 45-degree angle towards the green side of the plate in asura.
Make sure there are ample supports to hold the structure of the part during the riggers of printing.
Cause: dust/slicer/small debris