Oh I don't know about BIP-42. Just checked it out.

So it's due to that we have to stop at 32 halving ya?

I thought it would make more sense if miner get 0.5 Satoshi on the 33rd halving.

But now it seems clear to me that even if that was the original intention by Satoshi Nakamoto, it isn't possible due to C++ limitation right?

CMIIW I'm not a coder