You’re decreasing total performance by using RAID0 if workload (farming) can utilize all individual disks at the same time. RAID0 is not free (though it is cheap) and abstracts away hardware from the application, which is useful sometimes, but Subspace farming can make better decisions performance-wise when it sees how many physical disks you have and parallelize things appropriately without hoping that RAID0 will work in the most optimal way for this use case.
The issue is with plotting there, not farming, see Creating plotts error
Is that from smaller plot size or the same plots that were not farming before?