Most popular variants of the header value (we only show this when there's just a bunch of variants):

Content Security Policy is used by a web server to declare a list of trusted content types (images, scripts, media etc) and origins from which they can be safely loaded as intended by the website authors. The Content-Security-Policy-Report-Only header instruct the browser to enable CSP in enforcement mode.

Reference...

We have seen 0 websites setting the Content-Security-Policy HTTP header and 0 unique values of this header.