Every consensus mechanism has tradeoffs and weak points, of which Proof-of-Space has many. However, Chia has integrated two elements to enable protection: grinding and long-range attacks.
The most common grinding attack is when an adversary continuously computes info about the tip of the blockchain until they can extend the next block over others. The grounding networks can get beholden to the grinder.
There are a few tricks to combat grinding in Chia Network:
The data and consensus layer are separate but connected with a unique private key. Chia claims the uniqueness of each sign-off protects the underlying consensus layer from grinding.
A time delay function (VDF) is infused into the consensus layer between every Proof-of-Space.
The VDF acts as a checkpoint for the Chia network. It is necessary as an adversary wishing to conduct a deep hard fork on the network needs more than just a large amount of space used for farming, but also need to compute each VDF along the way.
And, by design, VFDs require resource-intensive computation. A VDF is a function that takes a set amount of time to compute and can not get parallelized. Chia expects ASICs to be created for VDF computation, although the network requires only a few VDF creators (called Time Lords) to run smoothly. Moreover, Time Lords earn no Chia for creating these proofs.