Hmm interesting. Did you happen to change a compat date or any other flags or did it start erroring
Hmm interesting. Did you happen to change a compat date or any other flags or did it start erroring without any changes on your end?

From reading up I see that fetching other workers in the same domain can cause problems and that's why service bindings where introducedA Tunnel isn't a worker though, unless you have another worker in front of it or anything?
not using the cfargotunnel, I have dns cname in place.cname is proxied right? Do you get the exact error code it returns (ex: 502, 520, etc)
await fetch("http://tunnel.example.com/localapi/files", {
method: "POST", etc