In 2016, a flash shortage of NAND started. The shortage is partly the result of demand, but it is also due to the shift of vendors from 2D or planar NAND manufacturing to much denser 3D NAND technology. Making 3D NAND chips is a trickier process.
NAND flash vs. NOR flash
NAND and NOR flash memory are the two main types of flash, which get their names from their respective logic gates. NAND flash memory is written and read in blocks smaller than the computer, while NOR flash memory reads and automatically create bytes. NOR and NAND flash memory use cases include laptop and desktop computers, digital cameras and audio players, manufacturing, and medical electronics.