The Tag Helper opt-out character ("!") should work when we use it razor outputs a target tag as is. I have no idea why you face it. It might be related to browser caching. Let's try to add cache busting for the script path just to be sure.
I fetch the error when try to load js and css files. In nopcommecre 4.40 I was use simple way to call it <link rel="stylesheet" href="~/Plugins/Payments.NamePayment/Content/file.css" /> <script src="~/Plugins/Payments.NamePayment/Scripts/file.js"></script>