What do you do for synching validations between front-end and back-end teams in laravel?

I read this post but I would like to know about laravel.

I have also seen laravel js validation package but the problem is that front-end and back-end projects are not the same. The front-end project has been written in vue.js.

As a second question, what about the case that my validations exist in the database instead of the formRequest? e.g., I have an API to show items. These items have several regex validations. It is not secure to send them along with items. What should I do?