Bottom surface of a model seems to be missing

[new3dprintinguser]

Hi, I printed a model downloaded from the internet. The raft layer was set to 2 or 3. After the print was completed, I removed the model from the coarse build plate of my Prusa i3 MK3s. Then, it looks like the bottom surface of the model was not printed as I could see the internals of the model. What happened? Any suggestion on how to fix this issue?

[fred_dot_u]

At first glance, your problem is with underextrusion on the first layer. If the other layers are okay, consider to check your bed leveling/nozzle clearance and your slicer settings. You mention a raft, which implies that you've removed the raft to take the photo. Do the first layers of the raft appear complete? If they are better than what you show in the photo, I'd aim at the slicer settings. If you have a genuine Prusa Mk3s, you should be able to print without a raft.