mgaert Is this still an issue? Did the above solution help? You can also modify that from your Jenkins instance's script console by using System.setProperty("hudson.model.DirectoryBrowserSupport.CSP","sandbox allow-scripts; default-src 'none'; img-src 'self' data: ; style-src 'self' 'unsafe-inline' data: ; script-src 'self' 'unsafe-inline' 'unsafe-eval' ;").
By default, Jenkins is very restrictive on permissions for external reports, so those permissions need to be relaxed, or you need a resource root URL for your Jenkins instance to display reports.
Use this JVM option:
-Dhudson.model.DirectoryBrowserSupport.CSP="sandbox allow-scripts allow-same-origin; default-src 'none'; img-src 'self' data: ; style-src 'self' 'unsafe-inline' data: ; script-src 'self' 'unsafe-inline' 'unsafe-eval' ;"