Also the self patching back into protected mode! ugh - good thing they ordered more than one!
Doesn't the protection usually work such that it prevents reading the firmware but still allows you to erase and reflash it?
Assuming the other commenter is correct and the mcu is a clone of an ST product, then it's possible that the protection are fuses that destroy the pathways to the memory. They're one-time writable and cannot be undone. At my work that is how we protect our firmware with a similar ST product.
I'm not sure how it works in-silicon. Would be interesting to know how... but it's sunday afternoon
Blame STM. Those clones copy (..among other things) the naming convention from STMicroelectronics parts like stm32f103c8t6/stm32f103cBt6. Guess what's the only difference between those.
Oh, and .. since STM likes binning/product segmentation, there's a good chance that if you ignore the reported flash size and still try to flash the full 128K, it works on those models..
An 8 looking almost exactly like a B. What a terrible idea.