As the web is evoling more and more, new features are implemented to make it more secure and prevent most common attacks.
One of the features implemented, that is still trying to become default on all websites, is Content security Policies or, in short CSP.
Implementing CSP on your website is rather easy; understanding what you are doing, what is being blocked and how to fix it, is not easy at all.
Firefox and Chrome only inform you which policy is blocking a specific content: css, frame, script; it is then up to you understand your pages and look exactly what is being blocked; This is not easy at all.
What is more alarming is that some of the teams / companies, after being informed their software is being blocked by some CSP, their solution is to ask you to relax you rules.
Hopefully there will be some improvements on this: CSP can help you prevent most of XSS attacks, therefore I do not know of any good reason of not implement them properly and request vendors - open source or not - to fix and adapt their software to such good practices