"Endurance is also a weak spot for QLC flash"
There's also the crucial issue of data retention. All these multi-bit per cell devices use an essentially analogue data detection method -- QLC has to be able to discriminate 16 discrete voltage levels per cell. So the inevitable effects of charge leakage (albeit slow) will eventually be felt. The more 'bits per cell' the sooner that will happen because the differences between the bit levels are smaller, and 'error correction' can only do so much. Furthermore, the higher the device capacity the greater the chance that some leakage related data corruption will occur, simply because the target is bigger, so we're sacrificing reliability for convenience yet again.