Nextcloud + Cloudflare Tunnel css or js not being loaded

Images are probably better to describe my issue. I’ve installed Nextcloud + Cloudflare Tunnel, URL works, already had a domain so using subdomain. The problem starts after I login into Nextcloud.
See the attached image. On local all good, on (proxied?) URL via cloudflare something gets broken while loading, either CSS or JS.
Am I forgetting to add something on config.php? Please help!