Setting firebase secrets from JSON

So I am trying to update a secret to my project. It is JSON string. On windows it is not even possible. I kept getting the following error:

Error could not parse secrets: 'PRIVATE': must be in the format NAME=VALUE

I ran WSL ubuntu terminal, where I was able to set the secret. I have escape the quotes(") for the keys, but it worked.

"{ \"key\": \"value\",...}"

However on deploy I get the following error at run time:

json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

The app was imported form heroku, which already had an env var that was just a json string. How do I assign the data to a secret?