Hi @lucasjohnson. Well, certainly you can use whatever names for your environment variables that you wish. The links that I shared reference Netlify’s and Vercel’s documentation, which should be able to guide you through viewing and updating the environment variables they have stored for you in the cloud. You will need to make sure that they are the same as the ones you are using locally, or otherwise set to the values that you desire.
For example, I shared with you that you can run a CLI command to list the environment variables they have saved for you. You can also view the variables stored with Netlify on your Netlify project page. Their documentation goes into greater detail.
For Vercel, I shared their documentation page for environment variables as well. It states that to declare an Environment Variable for your deployment, head to the Environment Variables page of your Project Settings.
Please confirm that the environment variables for your Netlify and/or Vercel projects have been correctly assigned. You said that your application works locally, so it sounds most likely that the variables have not been set for your production environment.