Your memory chips inside the SSD is failing. Reallocated sector in NVM (non-volatile memory) chips means that certain sectors inside the memory chips are unusable.

Construction of an SSD
1. SSD controller - The main brain of the SSD.
2. Memory chips - Multiple memory chips mounted on the PCB, along with the SSD controller. It could be 2/4/6/8 or more chips depending on the size of the SSD. Inside a memory chip, it will be divided into multiple number of sectors.

Technical explanation, laymen terms as much as possible
When the SSD controller identifies that certain a sector in the memory chip unusable (either unable to read or write properly), it will write off that sector as bad sector, making it unusable to the system. The SSD controller will then mark that sector in that particular memory chip as off-limits (SSD controller has its own memory to record such bad sector). Any read and write operation will not be used by the SSD controller anymore.

Obviously, writing off a sector in the memory chip will cause a decrease in the storage capacity. This is where overprovisioning comes in. Once the SSD controller mark off a sector as bad, it will then find some other reserved sectors as replacement. Hence, the term overprovisioning, where some reserved sectors become available by the SSD for usage.

The Reported Uncorrectable Errors of 198 sectors is worrying as that much number of sectors involved could indicate multiple memory chips inside the SSD are failing.

The 64 sectors that were reallocated could all be from the same one memory chip. However, there is also a possibility that multiple memory chips that has failing sectors which made up the total number of 64 reallocated sectors. This information is not visible to the end user. The end user will only be able to see the total number of reallocated sectors reported by the SSD. The manufacturer will be able to tell the exact failing chip or multiple chips by accessing the information stored inside the SSD controller.

Why it is happening?
Latent defect at the silicon level inside the memory chips. An accelerated number of reported sector reallocation count, from 32 to 64 within a span of a day means that the defect propagate throughout the memory chips.

Solution
Claim warranty of the SSD if it is still available. And don't use it for important data backup. Kingston UV500 series are budget line SSDs. Budget line means cost-saving on manufacturer side to be able to sell them at such a low price. The memory chips used could be chips that are lower performance threshold during the manufacturing testing.

This post has been edited by SFX: Mar 4 2021, 11:41 AM

No. Based on the Kingston UV500 datasheet, your 480 GB will have an endurance rating of 200 TB writes over warranty of 5 years. Meaning that 200 TB worth of data can be written into the SSD before it is likely to fail (during the 5 year warranty period). Important keyword here: before it is likely to fail.

Common consumer application, like you, who use it for data storage, doesn't incur too much writing. Reading operations are much more common.

Another parameter is the Read Error Rate, which shows a value 6.12 million (6128887) attempts of read encounter issue. When it encounter read failure, it will try to correct the data itself automatically (Soft ECC correction value of 6128689).

So, your main failure on this SSD is actually the read operation.

Side technical explanation: Read operation uses sensing circuitry inside the memory chips to read the voltage level stored inside the bit cells. It could be a defective sensing circuitry or the memory cells itself unable to hold the charges.