Preview API Access

But if you are using the Browser Preview API, you will need to set up your allowed preview hosts. These are the hosts where you will be mounting the iframe, for example localhost:5173 or company-domain.com. Configuring these hosts using the SDK CLI. The hosts are stored on your workspace and applies to all your Sandboxes.

$ csb preview-hosts list
 
$ csb preview-hosts add :host
 
$ csb preview-hosts remove :host
 
$ csb preview-hosts clear

The :host is a JavaScript RegEx. So you can set your host as: "my-project-.*-.*.vercel.app" for example (Note the quotes).