How to pull a nested Document

Referring to this Question, Now I want to remove dinner from Random Name 2, how can I do that: Here's what i tried:

din_val = data[0]
condition = {
    "username" : session['user']["username"],
    f"likings.{din_val}" : {
        "$exists" : True
    }
}
update_value = {
    "$pull" : {
        f"likings.$" : din_val
    }
}
response = mongo.db.appname.update(condition, update_value)

But the error I am receiving is
pymongo.errors.WriteError: Cannot apply $pull to a non-array value, full error: {'index': 0, 'code': 2, 'errmsg': 'Cannot apply $pull to a non-array value'}