Data is in raid0, probably a btrfs issue, does not always calculate correct spaces for pools with different size devices, but all the space should be usable.
Since Unraid supports a lot of pools I would recommend using smaller pools, i.e., I also do some "farming" and have for example 6x1TB, 5x2TB, 3x3TB, 2x8TB, etc, they all have a share called plots, so no need to add each pool separately to Chia and it's much easier to manage, also if there's a disk problem you only lose one pool.