This usually happens when the landscape (or destructible object) becomes too thin. Chaos needs some thickness to generate stable fragments. If it’s too thin, fragments become unstable and start floating or acting weird.
Try converting the destructible part of your landscape into a solid static mesh with proper thickness (30–50 cm).
In your Geometry Collection, make sure you increase the minimum mass and enable “Mass as Density”.
Also, check your Chaos Field strength and radius, they might be too high.
Landscapes aren’t ideal for Chaos destruction, so using a custom mesh will give you more control. Hope this helps!
Doc about Chaos Destruction
https://dev.epicgames.com/documentation/en-us/unreal-engine/chaos-destruction-in-unreal-engine?application_version=5.4
I found something in the forum that can help you a lot.
If you’re still facing challenges or have new questions, feel free to share.