This could potentially be mitigated by observing vote activity from IP ranges and frequency. Throttle vote activity for a range based on frequency over X window of time. Banning accounts could help, too, as well as more stringent account verification (e.g., want to enable voting on this account, give us a phone number or other form of 2FA).
It could get murky, but you could even have votes weighted by an account score (not quite sure how that would take shape).
They’ll give you a phone number then and enter totp and solve captcha. And click as organically and humanly as google is concerned, with sleep schedules and days off, with click hesitation and cursor movement profiles. It’s not that big of a deal, all instruments are available.
