Can't SAVE edits to forms

I have a form that works fine, but when I go to make a change and SAVE, I get a notification from the web hosting company that “This site has a security violation” – I rang the web hosting company and they said that there is malicious code connected to this plugin and that’s why they are blocking any changes. They said I need to “optimise the code” of the Visual Form Builder plugin. How do I do that?

https://ww.wp.xz.cn/plugins/visual-form-builder/