You can enable <a href="https://modules.prosody.im/mod_firewall" target="_blank">mod_firewall</a> on your Prosody server. For more information, please check <a href="https://livingston.frama.io/peertube-plugin-livechat/documentation/admin/mod_firewall/" target="_blank">the documentation</a>.
Here you can configure Prosody <a href="https://modules.prosody.im/mod_firewall" target="_blank">mod_firewall</a> module. You can create multiple configuration files bellow, and change their order. Don't hesitate to share your configurations with the community (for example by adding some examples in the plugin documentation).
Warning: mod_firewall is disabled in the livechat <a href="/admin/plugins/show/peertube-plugin-livechat" target="_blank">plugin settings</a>, you have to enable it if you want this configuration to be taken into account.