OK after further poking the above message appears to be related to how PowerShell was interpreting strings. I switched to CMD and got the following:
curl https://api.coinbase.com/v2/accounts/<account>/transactions -X POST -H "Content-Type: application/json" -H "Authorization: Bearer <token>" -d "{ \"type\": \"request\", \"to\": \"<email@address>\", \"amount\": \".0001\", \"currency\": \"BTC\" }"
Results in:
{"errors":[{"id":"invalid_request","message":"Missing parameter: `type`"}]}
This is the same error message as reported in 2019:
