Removing quotation marks in json file python

I accidentally double encoded a json file. Now i need to get rid of the quotation marks around its body. How can i do it ?

The Json I have looks like this:

'"{"created_at":"2022-06-03T13:00:52.000000Z","created_by":"foo","event":"foo"}"'

And I need to look it like this:

{"customerId":"foo","mobile":"foo","projectId":"foo"}