I've shucked over 40 Seagate External drives. 28x4TB + 5TB and 12x8TB.
The 4 and 5 TB ones were all PMR drives.
The 8TB Backup Plus ones I bought off Amazon were all Seagate 'Compute' PMR drives that run at 200MB/s down to 90MB/s Model number ST8000DM004-2CX188.
The 'identical' Backup Plus 8TB ones I bought off Ebuyer were both Seagate SMR 'Archive' drives that run at 180MB/s down to 30MB/s.
So they use whatever they have that month I think. But Amazon seem to get the faster 'compute' drives.