STMicro STM32 microcontrollers are very popular, and it's a well-known fact there are some fakes on the market. What I did not know is that many don't even pass the blinky test.
I learned this in Greaseweazle Github repository, a "tools and USB interface for accessing a floppy drive at the raw flux level", where keirf explains how to detect STM32 fakes, notable clones of STM32F103C8 found in Bluepill board.
What a real STM32F103C8T6 MCU Looks Like
The photo above shows a real STM32F103C8T6 microcontroller, and all should have the similar top marking