To prevent spammers from posting ads and curses in your forum, a CAPTCHA can help, but it's not 100% reliable. Blocking IPs works to an extent but isn’t foolproof either. Have you tried the Anti-Spam Filter for Gravity Forms? It’s great for advanced filtering—blocks keyword-based spam, Cyrillic text, and lets you customize protection for specific forms. It’s super easy to use and highly effective!

https://wordpress.org/plugins/anti-spam-filter-gravity-forms/