thanks to the forest team who solved my problem. I am pasting below the message I received in case it might be helpful to others as well.
" In your setup, you're using a large Spline Area in the Include mode with the surface as a base to 'cut' it - this combination might not be ideal. In the revised version of your scene, I've adjusted the Spline Area to cover just the desired area, which seems to resolve the issue. Also, I've lowered the Transform > Translation values a bit."
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