I noticed that my CSP reports don't have a release tag and I'm wondering if it's possible to add one.

CSP errors typically originate from browser-generated reports (via the report-uri or report-to directives in your CSP configuration). These errors are not directly tied to your application's JavaScript runtime, which means they don't have access to or include your Sentry SDK's metadata, such as the release tag.
​
The browser sends these reports independently of your app's Sentry setup and because of this, they don't have context about the app's release or environment because they are pure HTTP POST payloads to your reporting endpoint.