WD Red is an SMR disk - and even WD state that it is NOT suitable for ZFS.
See Read and Write slow RAIDz1- truenas scale - #6 by Protopia for a detailed explanation I researched this morning.
SMR disks have bulk write performance issues where they have c. 30GB of CMR space for caching writes and the data is then staged to SMR over time. If you are bulk writing i.e. during a resilver, the CMR cache fills up and then writes get massively delayed and the drive appears to be faulty to ZFS.