Depends on the language. Current standardized American English overwhelmingly list adds -s
/-es
to make a plural noun. So “octopuses” would be technically correct with “octopodes” and “octopi” also accepted.
If you’re writing Latin, you’d want octopi instead. If you’re writing Greek: octopodes.
But English is a democratic language, so feel free to vote often and early by using your preferred version.
it’s never happened to me my whole life