Okay so you have then both pointing to an IP – is it the correct IP?
Even when proxying the traffic through Cloudflare, the server still returns a 404. This is something the server is doing, not Cloudflare.
Is this your own server, like a VPS? Do you have shell access to it? Or is it a web host?
Have you checked the configuration on the server? Have you checked the logs on the server?
If it’s your server, you should be able to determine why it’s returning a 404. If you don’t have proper access to the server you may have to ask the server owner to take a look.
Your “traefik” subdomain returns a 403 instead of a 404 – again, this is a direct response from your server, the traffic is not actually passing through Cloudflare anymore and the issue persists, so you’ll have to check configuration & logs on the server