Going back on the source video (PinStratsDan was one of a few players that it happened to), it just wiped out the score before adding 10 million + 10,010 from the left inlane switch.
Hearing the audio cue on the playback, Bud goes “TEN----TEN” instead of “TEN—MILLION!” I don’t know if that’s a ROM issue; I tried replicating it on Pinball Arcade and it added 15 million every time. Since Zen works with powerups on a separate game mode, I’m not sure if their code is working directly with the Williams ROM or not. It is an official ROM, since I’m able to use flipper codes to initiate the credits sequence.
Some players had their scores up to 100m+, maybe 200 or even 300 million, with their scores reduced. There’s no other thing I can think of apart from Quick Jackpot that has bugged scoring. I tried replicating it on Pinball Arcade, but Bud’s callout works correctly and awards 15 million-ish instead of the 10 million cap.