@highvoltage 😂 I have to admit that I use that feature only once or twice a year, and thinking about it now, I remember that when it did not work for my second monitor, I didn't care at all. It did not even occur to me to be a "bug".
But if you like it, then It seems there is an extension that may help you:
https://github.com/G-dH/custom-hot-corners-extended
It explicitly mentions multi-monitor support, but I did not test it.