Interesting conversation about Western Digital "Red" HDDs for # devices https://freeradical.zone/@tek/104037571132363249 ... he links to [1] in the OP.

"Western Digital, Seagate and Toshiba have begun selling SMR drives without labeling them as such, thus revealing a large controversy, as SMR drives are much slower in some circumstances than PMR drives.[9] These practices were used to be in both data storage-dedicated (for servers, NASes and cold storage) and consumer-centric HDDs." [2]

Also, #: SMR (Shingled magnetic recording) [3], PMR (Perpendicular magnetic recording) .

The OP explains why this is an issue in [4] and [5] and [9].

Also, # (Today I learned) the terms: LMR (longitudinal magnetic recording [6], and PMR (Perpendicular magnetic recording) [7] ... I already knew generally about both processes, but did not have specialized terminology for them. (CMR [8] is a rename of PMR.)

References:
[1] https://blog.westerndigital.com/wd-red-nas-drives/
[2] https://en.wikipedia.org/wiki/Shingled_magnetic_recording
[3] https://www.storagereview.com/news/what-is-shingled-magnetic-recording-smr
[4] https://freeradical.zone/@tek/104037775889323461
[5] https://freeradical.zone/@tek/104037804715066031
[6] https://en.wikipedia.org/wiki/Magnetic_storage
[7] https://en.wikipedia.org/wiki/Perpendicular_recording
[8] https://blag.nullteilerfrei.de/2018/05/31/pmr-smr-cmr-i-just-want-a-hdd-mr/
[9] https://freeradical.zone/@tek/104037879736589923

All the NAS units I've purchased (possibly excepting #'s, since I did not buy drives for him) also got WD Red NAS drives. Possibly they were older PMR/CMR drives, but since WD did not properly label their products, I do not know.