This usually occurs when the Laravel application tries to call itself but fails to establish a connection. There are several ways to solve this problem:

• try excluding /oauth/token from CSRF middleware
• Use the config function instead of env
• Change the url to localhost
• Use trim to remove unnecessary spaces and/or slashes
• Use url method
• Check with http prefix
• Try to call the route from an api client (postman, insomnia)
• Test on tinker