In your example, even if it you didn’t share it on social media but released it into the wild in back-channels and people started using it, the YT devs would figure it out eventually anyway. They would still notice downvotes happening and realize someone figured out a hack to enable that. Then they would scour the internet and dark web for it till they found it, either that or use telemetry in YT pages to reverse engineer it.

Also an idea like that is only useful if lots of people use it. If you only share it with your 5 closest friends, then their downvotes will have no effect on the total up/down ratios. But once lots of people use it, it becomes obvious to the YT team, and they figure out how to fix it.