Any event with public voting will eventually attract people who try to game it. The goal is not to be perfect, but to make abuse hard, visible and costly.
Make automation harder
Bot checks, hidden form traps and request throttling make scripted voting far less effective.
Be transparent about the rules
State plainly that manipulation can lead to disqualification. Most supporters will respect clear expectations.
Review unusual activity
Sudden spikes from a single source are worth a closer look before results are announced.