Every user that is not muted can vote.This means that you can prevent anonymous users to vote by using the ["{{% livechat_label livechat_configuration_channel_mute_anonymous_label %}}" feature](/peertube-plugin-livechat/documentation/user/streamers/moderation).
If "{{% livechat_label poll_anonymous_results %}}" is checked, votes won't be shown to other users.If unchecked, votes will be publicly visible as you will see message like "!1" in the chat.
For viewers using XMPP clients or outdated livechat plugin versions, the banner will not be visible.But they will see the message in the chat and will be able to vote by sending messages with their choices.