Admin URL Endless Loading

I have a headless CMS setup where my front-end is a NextJS application hosted at a parent domain, mydomain.com since my Ghost instance is on a separate server, I configured it to be pointed to admin.mydomain.com. I have made the necessary steps to config.production.json:

{
  "url": "https://www.mydomain.com",
  "server": {
    "port": 2368,
    "host": "127.0.0.1"
  },
  "admin": {
    "url": "https://admin.mydomain.com"
  },

and have gotten access via admin.mydomain.com/ghost/ when I first restart the Ghost instance on my server, but for some reason every other time I visit, I get the animated circle loading screen or login loading button on the sign in form. It isn’t until I run a command with my Ghost CLI to restart the server that it works briefly, but then the same issue later

When I look at the console logs it looks like there is (pending) request

Request URL: https://www.mydomain.com/private/?r=%2F

With an Origin: https://admin.mydomain.com

This feels like what might be hanging up the admin UI from loading, but not sure why it would be making that request.