but it still seems to be in the top 15 SSD drives according to Tom's Hardware SSD charts.. How did that happen?
A lot of SSD testing done by review sites involves short-term usage scenarios. This is similar to the way Consumer Reports tests appliances like refrigerators. It isn't uncommon for people to buy the top recommendations and find that they break just out of warranty.
TLC NAND degrades quicker than MLC and uses more power. HardOCP warns that the power usage may go even higher as the NAND ages. That site even suggested that Samsung start using a thermal pad because of heat generation.
This is the only SSD in the market to use TLC NAND. TLC (triple layer) also has the lowest lifespan. Anandtech estimates that the program/erase cycle lifespan may be around 750 cycles for 2xnm chips. As NAND processes continue to be shrunk, that lifespan will also shrink. MLC is being produced at 19nm already. Are we going to soon see TLC with 500 p/e cycles?
TLC NAND's performance may degrade significantly over its lifetime, especially if it is written to quite a bit. HardOCP found that steady-state 4k testing caused the 120 GB drive to even flatline on read speed, the one thing that TLC drives seem to do well in (unlike write speed). This is the first TLC product in the market. Your mileage may vary.