You can buy STM32s from LCSC (Chinese equivalent of Digikey). They're probably not fake - LCSC is a fairly established trusted manufacturer. China makes a huge

You can buy STM32s from LCSC (Chinese equivalent of Digikey). They're probably not fake - LCSC is a fairly established trusted manufacturer. China makes a huge majority of the world's electronics, and a big chunk of those will have ARM microcontrollers on them. Of course Chinese suppliers can get genuine ARM chips.