Are you refering to using www.salesforce.com instead of login.salesforce.com? If so, then there is no change because the only way to login to a sandbox is via test.salesforce.com
I'm refering to the email 'REMINDER: www.salesforce.com API login endpoint will be retired January 1' which talks about changing the API login from www.salesforce.com to https://login.salesforce.com. We also use API calls to our sandboxes, so I'd like to know if there is a login change needed for the logon from test.salesforce.com.
We also use API calls to our sandboxes, so I'd like to know if there is a login change needed for the logon from test.salesforce.com.