https://www.theregister.co.uk/2018/08/07/samsung_qlc_consumer_ssd/

Samsung has started mass production of the world's first QLC (quad-level cell) consumer SSD.

QLC is 4 bits/cell flash technology and a next step in cell bit capacity from the current TLC (3 bits/cell). Foundries belonging to Intel/Micron, SK Hynix and WD/Toshiba have started producing QLC chips and, in some cases, SSDs already. For example, Micron has a 7.68TB QLC SSD called the 5210 ION. SK Hynix has not yet confirmed any QLC technology developments.