i didn't nitpicking i ask a real question D:
It's not a bug. Sega either uses 16bit integers to store size of a stack, which has a hard cap of 65535 and they decided to cut it at 65000 as a round number to avoid overflowing, or while they can allow stacks to reach 4.294.967.295, they decided to settle for a smaller number which is workable with 16bit calculations too, because 10 digits do not fit in the UI at that place.
Either way, it's a intentional limitation by design.
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