QLC also has shitty slow write speed. (Slower then linear writes on spinning rust!)
So consumer SSDs now depend on a limited dynamic part of flash being used as SLC to cache writes. Just that this dynamic part mostly gets smaller the fuller the device is.
And as soon as you do anything with large writes you will hit a brick wall of slowness, on full devices sooner then on empty ones.
Yes many consumers will be fine with this drivers.
But the information about the limited write cache never gets mentioned by the manufacturers. So people that actually need to write large amounts of data from time to time, fall into a performance trap.
So consumer SSDs now depend on a limited dynamic part of flash being used as SLC to cache writes. Just that this dynamic part mostly gets smaller the fuller the device is.
And as soon as you do anything with large writes you will hit a brick wall of slowness, on full devices sooner then on empty ones.