[fest]

There's actually even more than this to low price. I have seen knock-off ST-Link dongles with STM32F103C8 MCUs that are not supposed to have enough flash memory for the stlink firmware, yet they functioned.

How? Turns out they physically have more flash memory, but the accessible flash area is limited by programming tools and documentation to 64KiB (most likely price segmentation, but maybe there's a flash page remapping mechanism that would allow to bin devices based on manufacturing yield).