Hi Gsglawon,
Apologies for getting late back to you.
Saving backslashes (\) directly through the JSON will not be possible, as application platform by default adds forward slashes ("\/"), double slash ("\\") by removing the backslash. It is recommended to have encoding before adding any value to JSON and decoding back after getting the JSON from the database.
Please use base64 encoding and let me know if you still face any issue while saving/fetching the value from the database.
Regards,
Himanshu Sharma