Expected file to have JSONL format, where every line is a JSON dictionary

I'm trying to upload a JSONL file to an API endpoint, however, I keep getting this error.

[{"error":{"message":"Expected file to have JSONL format, where every line is a JSON dictionary. Line 1 is not a dictionary (HINT: line starts with: "{...").","type":"invalid_request_error","param":null,"code":null}},{"object":"list","data":[]}]

The file I'm selecting to upload has the extension jsonl and is properly formatted

{
  "name": "Gilbert", 
  "companies": [
    [
      "Microsoft"
    ], 
    [
      "Amazon"
    ]
  ]
}
{
  "name": "Alexa", 
  "companies": [
    [
      "Apple"
    ], 
    [
      "Google"
    ]
  ]
}

However, when the file gets uploaded to the storage directory, it is being converted to .json and returning the extension also says json

// Controller
Storage::putFile('avatars', $request->file('file'));
return $request->file('file')->extension();

// Vue
<form @submit.prevent="submit">
            <input type="file" @input="form.file= $event.target.files[0]" />
            <button type="submit">Submit</button>
</form>

export default defineComponent({
    setup() {
        const form = useForm({
            file: null,
        })

        function submit() {
            form.post('/upload')
        }

        return { form, submit }
    },
});