The new driver detects clones, puts "THIS IS NOT PROLIFIC PL2303. PLEASE CONTACT YOUR SUPPLIER." in Device Manager, and refuses to work. What sequence of events do you see that would have led to that string existing, let alone all of that happening, unintentionally?
What I'm saying is that just "don't write code to try to detect clones, and treat every chip the same as you're currently treating official ones" would have been sufficient to make it work, and they intentionally did extra work and wrote extra code to make it not work on clones.
Again, you do not actually know that. If you read what I wrote earlier, then you would understand that there are plausible scenarios where no intentional breakage occurred.
