Maybe you can check your version of the browser, if it needs an update. Additionally, you can go through these documents.

[Reference][1] [1]: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_security_policy

[Reference][2] [2]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src