Thanks for posting query in Microsoft Q&A Platform.
If I understand correctly, you are looking for backing up PROD ADF. Please correct me If I am wrong.
Usually, Its not needed as your DEV ADF will connected to repo that release pipeline deploys this in to different environments. So if something goes wrong with other environments then we will be always having an option to re-run release pipeline or deploy from DEV ADF to other environments from scratch.
Still, for some reason if you would like to take backup of PROD ADF, then you can consider downloading ARM template of PROD ADF and keeping it in some backup location.
Please let us know how it goes or if any further quires.