Removing Watermark from PDF Merge

Which product are you using?
PDF.js Express Plus

PDF.js Express Version
UI Version = 8.7.0
Core version = 8.7.5

Detailed description of issue
I’m trying to use the PDF.js Express REST API to merge annotations onto a document and allow the user to download the resulting PDF. I have added the key the request but I’m still getting the watermark.

Expected behaviour
Expected to download PDF without the watermark or to receive an error if the wrong key is used.

Does your issue happen with every document, or just one?
Every document

Link to document
N/A

Code snippet

const data = new FormData();
data.append('xfdf', xfdf);
data.append('file', blob);
const licenceKey = getLicenceKeyForDownload();

if(typeof licenceKey === 'string') {
    data.append('key', licenceKey);
}

// Process the file
const response = await fetch('https://api.pdfjs.express/xfdf/merge', {
    method: 'post',
    body: data
}).then(resp => resp.json());

const { url, key, id, error } = response;
if(error !== undefined) {
    console.error(error);
}

// Download the file
const mergedFileBlob = await fetch(url, {
    headers: {
        Authorization: key
    }
}).then(resp => resp.blob());

I checked the documentation again and saw that data.append('key', licenceKey); was wrong. I changed it to data.append('license', licenceKey); which fixed the issue.

const data = new FormData();
data.append('xfdf', xfdf);
data.append('file', blob);
const licenceKey = getLicenceKeyForDownload();

if(typeof licenceKey === 'string') {
    data.append('license', licenceKey);
}

// Process the file
const response = await fetch('https://api.pdfjs.express/xfdf/merge', {
    method: 'post',
    body: data
}).then(resp => resp.json());

const { url, key, id, error } = response;
if(error !== undefined) {
    console.error(error);
}

// Download the file
const mergedFileBlob = await fetch(url, {
    headers: {
        Authorization: key
    }
}).then(resp => resp.blob());