python - truncating file in 'r+' makes the entire file rectangles

Question

The following is my code:

import json
id = "iderq23512345123521"
with open("file.json", "r+") as f:

        data = json.loads(f.read())
        f.truncate(0)
        del data[id]
        data = json.dumps(data)
        f.write(subs)

This is what the file looks like after I do it

When I try to copy and paste the characters, they don't show up

Answer 1

Rename the id variable to something else (like id2), id already is a python func