Checkbox list without using v-model

Vue has a good example of using multiple checkboxes with the same name attribute bound to the same array using v-model

However, I can't use v-model for some reason so I must use @input to emit checked while keeping the value unchanged.

Its not working for me though, all the checkboxes are checked/unchecked at the same time or I have to change the value which I don't want.

Is there a workaround?

Code: https://codesandbox.io/s/71pm2wllp1?fontsize=14