Doesn't it degrade with use? I thought with modern wear leveling you get degraded performance for a long time before it just stops working, but I'm no expert. I'd love to learn more about this actually
It does degrade, but not performance. The degrading happens when blocks hit their wear limit and can no longer be used. Flash memory typically includes additional blocks to replace those that are at their wear limit, but that will eventually exhaust and then the drive will be in a failure state. This can sometimes be that the drive stops working, or that it shrinks it's capacity, but the bandwidth and access speed characteristics remain constant throughout it's life.
That's determined by the firmware and the manufacturer.
Flash isn't like disks. You don't write to a block that's on a certain cylinder on a certain platter. You write a block and the memory controller determines where it will be stored, usually based on some wear leveling algorithm.
It's one of the reasons you can't securely delete a flash drive.
Handwaving about how flash is different than disks isn't an answer to how shrinkage is conveyed to the filesystem (and isn't a meaningful differentiator anyway, since common spinny-disks haven't been 1:1 mappings for well over 3 decades, themselves).
What may be the cause that the storage gets slower on older devices is, if they are nearly full. At least I heard this about SSDs. Please someone correct me if I remember this incorrectly
