You can disable paste in your input as follows:
html:
<input type="text" value="" id="myInput">
javascript:
window.onload = () => {
const myInput = document.getElementById('myInput');
myInput.onpaste = e => e.preventDefault();
}
Talking about security, I wouldn't say that this makes any impact. You would usually use client side and well as server-side validation of data submitted by the user.
