Explanation

Step 1: Create an empty environment variable named Custom Text Placeholder.
Applications often require different configuration settings or input parameters when deployed to different environments. Environment variables store the parameter keys and values, which then serve as input to various other application objects. Separating the parameters from the consuming objects allows you to change the values within the same environment or when you migrate solutions to other environments.
Step 2: Create a function to retrieve the value from the custom text placeholder and display the notification.
Step 3: Export the solution
You can manually export solutions. Microsoft recommends that you create an unmanaged solution to use for exporting your customizations, and then export your customizations periodically so that you have a backup in case anything happens.
Reference:
https://docs.microsoft.com/en-us/powerapps/maker/data-platform/environmentvariables
https://docs.microsoft.com/en-us/powerapps/maker/data-platform/export-solutions