Converting recevied body of axios POST to Blob/ArrayBuffer - node.js

Question

I have a React/Typescript frontend that is suppose to send a file to an Express backend via an Axios POST call. The Express backend is then suppose to forward the file to Azure storage. The Azure append method expects "a string, Blob, ArrayBuffer, ArrayBufferView, or a function returning NodeJS.ReadableStream".
However, what I receive on the backend (req.body) is not in any of those formats. I am not quite sure what is the format of the data received by the backend is in and/or how to convert it to one of the required formats. The console.log(req.body) for a very simple image gives the following
[Object: null prototype] { '�PNG\r\n\x1A\n\x00\x00\x00\rIHDR\x00\x00\x00#\x00\x00\x00"\b\x02\x00\x00\x00Z���\x00\x00\x00\x01sRGB\x00��\x1C�\x00\x00\x00\x04gAMA\x00\x00��\x0B�a\x05\x00\x00\x00\tpHYs\x00\x00\x0E�\x00\x00\x0E�\x01�o�d\x00\x00\x00\x1AIDATHK��\x01\x01\x00\x00\x00� ��nH#\x00\x00\x00��\x01\x0E\x14\x00\x01\x05?��\x00\x00\x00\x00IEND�B`�': ''}
I tried setting Content-Type to multipart/form-data (and using formData.append as is done in this post How to post a file from a form with Axios) or setting Content-Type to file.type; however, in those cases I just receive empty object ({}) on the backend for req.body.
Frontend
const onHandleChange = async (event: any) => {
const file: File = event.currentTarget.files[0];
axios
.post("/api/files", file, {
headers: {
"Content-Type": "application/x-www-form-urlencoded",
},
})
.then((uploadResponse: AxiosResponse | Promise<AxiosResponse>) =>
console.log(uploadResponse)
);
};
return (
<>
<p>Demo</p>
<form>
<input type="file" id="fileField" onChange={onHandleChange}></input>
</form>
</>
);
Backend
router.post('/', async (req, res, next) => {
try {
const datalakeServiceClient = new DataLakeServiceClient(
`https://${ACCOUNT}.dfs.core.windows.net`,
defaultCredential
);
const fileSystemClient = datalakeServiceClient.getFileSystemClient(FILESYSTEM);
const fileClient = fileSystemClient.getFileClient('simpleFile');
const content = req.body;
const length = parseInt(req.header('Content-Length'));
await fileClient.create();
await fileClient.append(content, 0, length); // This line expects Blob/ArrayBuffer, etc. and gives the error
await fileClient.flush(length);
console.log('Done');
} catch (error) {
throw new Error(error);
}
});