Hi @Community Alums ,
it actually depend on if you have remembered to take back-up of your custom configuration and development work. This can be done through a GIT for scopes application or update sets for global applications. If you haven’t remembered to take backup of your work then yes - your work will be lost if you release your instance.
if my answer has helped with your question, please mark my answer as accepted solution and give a thumb up.
Best regards
Anders
