There is a lot of discussion on this forum & questions about zpool not reporting/releasing all the space from deleted files. I experienced this first hand. I have a 4TB pool for media files. It got filled up to 95%. I created another pool (8TB) moved some of the files (200GB) to the new pool. Zpool reported about 24GB of additional space. I tried this several time with moving additional files. Each time zpool reported a fraction of the deleted files storage. I move all the file to the new pool and deleted and recreated the old pool. I copied all the files back to it, zpool reported approximately 800GB more available storage space than prior to reformatting. I verified that all files were copied. This is just an observation.