There are a lot of settings that can affect your DM.
For instance:
Damage Spread: 0.1 is a low value by default, but if a large enough force hits or causes damage it will transfer to surrounding chunks with enough force to break them free. Try a lower value or 0 to prevent any damage from spreading to other chunks in the DM.
Impact Velocity Threshold: use this to control the speed an object must be traveling to cause damage. Higher values can help from low speed impacts from destroying an object.
Damage Cap: This is helpful to keep Damage within an certain range. For instance, if an object receives a large force of damage it will only apply up to this amount of damage.
Support Depth: The depth at which chunks will “stick” together until they receive enough force to be broken free.
Minimum Fracture Depth: try adjusting this as well to get more refined destruction at specific depths. Only useful with DMs that have more than 1 depth layer.
Feel free to post your DM settings and I’ll have a look when I can, but no promises.