It tends to pop up on the forums from time to time. How large are these bubbles?
What you could try:
Delete the shadow effect
Create a new fill for these objects in the appearance panel: black
Move fill below the white fill
Apply transform effect to move to bottom right
Apply Gaussian blur effect to smooth.
Between 500 - 600mm.
Okay i will try it, thank you.
Does it get better in CPU preview?
How is Effects > Document raster effect settings set up?