I've been testing the native integration with Cloudflare tunnels in the new version 1.55.0, but there is a small bug.
Apparently, when you create a new "Cloudflare Tunnel Rule" in a domain you must always enter a subdomain, otherwise the response gives a 400 error.
Looking at the EasyPanel logs, it seems that the request made to Cloudflare is always sent "<subdomain>.<domain>", so if the subdomain is empty ".<domain>" is sent and the Cloudflare API responds with a 400.
Otherwise the integration works wonderfully well.