iframe CSP or x-frame options protections?

[albjeremias]

Describe the bug

Im using discourse, and trying to add an iframe of opensondage instance. but i get an error in firefox

Context

• Hardware: VPS online
• YunoHost version: 3.8.6
• I have access to my server: SSH
• Are you in a special context or did you perform some particular tweaking on your YunoHost instance?: i dont think so

Steps to reproduce

1. Add the domain name of opensondage in the confgurations of discourse... In discourse:
   1.1 - Go to Configurations -> search for "iframe" -> add your domain name in there. don't forget to hit the check to save!
   1.2 - Add open sondage as an iframe on a post: <iframe width="100%" height="500" src="https://domain_opensondage/studs.php?poll=soqGfM2NjNOreiHJ" frameborder="0"></iframe>

I get this error message, if i hit "Learn more..." I go to this page:

https://support.mozilla.org/en-US/kb/xframe-neterror-page?as=u&utm_source=inproduct

Expected behavior

I expect to have an iframe of opensondage, like i have for codimd pads! :)