defining custom domain in routes parameter in wrangler.jsonc impacts local host

Context:
- I have added a custom domain as the top level param to wrangler.jsonc

"routes": [
    {
      "pattern": "mydomain.com",
      "custom_domain": true
    }
  ],

"routes": [
    {
      "pattern": "mydomain.com",
      "custom_domain": true
    }
  ],

Issue:
- This impacts the host worker THINKS it's own during local dev when running with

wrangler dev

wrangler dev

How come this is undocumented? I had to guess why did my locally running worker redirects to the production domain - WTF??

Am I missing something?