For most customers, we see the use of the Cloud API v1 to manage their applications with scripts that live outside of their applications.
Check your application code
Check within your application for references to Cloud API v1 and then search your code for any usage. To call any endpoint with v1, it would need to include the following:
Searching for the above may be easier to track in your codebase using your text editor.
Look for Cloud API Drush commands
One of the more critical items to look for in your application is going to be the Drush commands for Cloud API V1.
These Drush commands could be used in Cloud Hooks, for example, to complete certain processes that your teams have designed when deploying to Acquia Cloud.
If you do find Cloud API v1 references, please see the following documentation for ways to migrate to the v2 version of the Cloud API: https://docs.acquia.com/acquia-cloud/develop/api/migrate/ . Note that not all v1 endpoints have equal Cloud API v2 endpoints available. If you have deprecated Cloud API v1 endpoints with no counterpart, this will also need to be taken into consideration.
Acquia BLT does not by itself implement the Cloud API, but you may have added code or scripts to your codebase that do.
Acquia Dev Desktop
A new release for Acquia Dev Desktop will be released on March 18, 2020. Please see the following documentation for more information: Switching to Acquia Cloud API v2 with Acquia Dev Desktop