Checkbox Not working

Where on the site do you have the form having the issue?

It’s at (REQUEST A PROPOSAL SLIDER) RIGHT SIDE OF THE WEBSITE.

What other plugins and theme do you use on the site?

Plugins: https://pasteboard.co/Bvkzhjr7GzEs.png
Theme: Bili

Try switching to the default theme, deactivating all plugins excluding Contact Form 7, Really Simple CAPTCHA, WordPress Importer and Yoast SEO, and clearing all cache data.

Why you are advised to deactivate plugins and switch to the default theme.

Thank You got it. It caused due to the theme that I’m using.