Do both websites use the same code (i.e. cotedegranitrose.net is a parked domain of cotedegranitrose.epizy.com)? Or the same database at least?
The reason why the subdomain works and the own domain doesn’t is because your website is configured to only work on http://cotedegranitrose.epizy.com/. This means that all URLs on your website use cotedegranitrose.epizy.com, not cotedegranitrose.net. And since hotlinking/embedding files from other free hosting websites is blocked, this means that only cotedegranitrose.epizy.com will work.
The easiest way to fix this is to edit your WordPress settings and update the Website URL to http://cotedegranitrose.net That will fix the custom domain, but it might break the subdomain. So you may want to make a decision about which URL you would like the site to be available on.